flow: update `better-sqlite3` types for v7.0.0 (#1770)

Summary:
I first wrote these type definitions for v4.x.x. The library API has
changed since then. This patch updates the type definitions to match the
current API as of the v7.0.0 release:
<https://github.com/JoshuaWise/better-sqlite3/blob/v7.0.0/docs/api.md>

There are breaking changes, but none among functions that we use. On the
other hand, there are new features that will be useful to us.

Test Plan:
Running `yarn flow` still passes. There may be some errors among typing
of functions that we don’t actually use (particularly `aggregate`, which
is more complicated than the others). If so, we can cross those bridges
when we come to them.

wchargin-branch: flow-better-sqlite3-v7-api

flow-typed/npm/better-sqlite3_vx.x.x.js

@@ -13,15 +13,24 @@ declare class bettersqlite3$Database {
     options?: bettersqlite3$Database$ConstructorOptions
   ): void;
   prepare(source: string): bettersqlite3$Statement;
-  exec(source: string): this;
-  transaction(sources: $ReadOnlyArray<string>): bettersqlite3$Transaction;
-  pragma(pragma: string, simplify?: boolean): any;
-  checkpoint(databaseName?: string): this;
-  register(fn: (...args: any[]) => any): void;
-  register(
-    options: bettersqlite3$Database$RegisterOptions,
+  transaction<R, A>(f: (...A) => R): (...A) => R;
+  pragma(pragma: string, options?: bettersqlite3$Database$PragmaOptions): any;
+  backup(
+    destination: string,
+    options?: bettersqlite3$Database$BackupOptions
+  ): Promise<bettersqlite3$Database$BackupProgress>;
+  function(name: string, fn: (...args: any[]) => any): this;
+  function(
+    name: string,
+    options: bettersqlite3$Database$FunctionOptions,
     fn: (...args: any[]) => any
-  ): void;
+  ): this;
+  aggregate<T>(
+    name: string,
+    options: bettersqlite3$Database$AggregateOptions<T>
+  ): this;
+  loadExtension(path: strin, entryPoint?: string): this;
+  exec(source: string): this;
   close(): this;
   defaultSafeIntegers(toggleState?: boolean): this;
 
@@ -29,18 +38,44 @@ declare class bettersqlite3$Database {
 }
 
 declare type bettersqlite3$Database$ConstructorOptions = {
-  +memory?: boolean,
   +readonly?: boolean,
-  +fileMustExist?: boolean
+  +fileMustExist?: boolean,
+  +timeout?: number,
+  +verbose?: ?(sqlText: string) => void
 };
 
-declare type bettersqlite3$Database$RegisterOptions = {
-  +name?: string,
+declare type bettersqlite3$Database$PragmaOptions = {
+  +simple?: boolean
+};
+
+declare type bettersqlite3$Database$BackupOptions = {
+  +attahced?: string,
+  +progress?: (bettersqlite3$Database$BackupProgress) => number
+};
+
+declare type bettersqlite3$Database$BackupProgress = {
+  +totalPages: number,
+  +remainingPages: number
+};
+
+declare type bettersqlite3$Database$FunctionOptions = {
   +varargs?: boolean,
   +deterministic?: boolean,
   +safeIntegers?: boolean
 };
 
+// The actual contract to `aggregate` is more complicated and dynamic
+// than can be expressed with Flow types. This is a "best-effort,
+// happy-path" type definition that is on the right track but will not
+// catch all errors. Consult the `better-sqlite3` API docs for the
+// source of truth.
+declare type bettersqlite3$Database$AggregateOptions<T> = {
+  +step: (T, bettersqlite3$BoundValue) => T,
+  +inverse?: (T, bettersqlite3$BoundValue) => T,
+  +start?: T | (() => T),
+  +result?: (T) => bettersqlite3$BoundValue
+};
+
 // Functions that accept bound parameters take positional parameters,
 // named parameters (passed as an object), or a combination of the two.
 // The named parameters can be placed anywhere in the argument list, but
@@ -72,25 +107,15 @@ declare class bettersqlite3$Statement {
   all(...params: bettersqlite3$BoundParameter[]): any[];
   iterate(...params: bettersqlite3$BoundParameter[]): Iterator<any>;
   pluck(toggleState?: boolean): this;
+  expand(toggleState?: boolean): this;
+  raw(toggleState?: boolean): this;
+  columns(toggleState?: boolean): this;
   bind(...params: bettersqlite3$BoundParameter[]): this;
   safeIntegers(toggleState?: boolean): this;
 }
 
-declare class bettersqlite3$Transaction {
-  +database: bettersqlite3$Database;
-  +source: string;
-
-  constructor(db: bettersqlite3$Database, sources: string[]): void;
-  run(...params: any[]): bettersqlite3$RunResult;
-  bind(...params: any[]): this;
-  safeIntegers(toggleState?: boolean): this;
-}
-
 declare interface bettersqlite3$RunResult {
   changes: number;
-  // TODO: This is actually `Integer.IntLike` from npm/integer, but we
-  // don't have those typedefs. For now, `number` is a good
-  // approximation.
   lastInsertRowid: number;
 }
 
@@ -107,7 +132,6 @@ declare module "better-sqlite3" {
   declare export type BindingDictionary = bettersqlite3$BindingDictionary;
   declare export type BoundParameter = bettersqlite3$BoundParameter;
   declare export type Statement = bettersqlite3$Statement;
-  declare export type Transaction = bettersqlite3$Transaction;
   declare export type RunResult = bettersqlite3$RunResult;
   declare export type SqliteError = bettersqlite3$SqliteError;
   declare module.exports: Class<bettersqlite3$Database>;