deploy.sh: depend on build_static_site.sh (#611)

Summary:
This is a minimal patch to make the deploy script depend on the
separate, well-tested build script introduced in #592. The patch
suggests a number of improvements that can be made to the deploy script
itself, but I’m deferring those as they’re not on the critical path.
These are tracked at #610.

Test Plan:
Apply the below patch. Then run `./scripts/deploy.sh -n`, and verify
that the served output is correct, including the CNAME file. Verify that
when the `DEPLOY_CNAME_URL` default value is removed, the resulting
output does _not_ have a CNAME file.

Patch, for ease of building:

```diff
diff --git a/scripts/deploy.sh b/scripts/deploy.sh
index cddcece..8925e5b 100755
--- a/scripts/deploy.sh
+++ b/scripts/deploy.sh
@@ -23,7 +23,7 @@ main() {
     preview_dir=
     trap cleanup EXIT

-    ensure_clean_working_tree
+    #ensure_clean_working_tree
     build_and_deploy
 }

@@ -76,8 +76,7 @@ build_and_deploy() {
     "${sourcecred_repo}/scripts/build_static_site.sh" \
         --target "${static_site}" \
         ${DEPLOY_CNAME_URL:+--cname "${DEPLOY_CNAME_URL}"} \
-        --repo ipfs/js-ipfs \
-        --repo sourcecred/sourcecred \
+        --repo sourcecred/example-github \
         ;

     sourcecred_site="$(mktemp -d --suffix ".sourcecred-site")"
```

wchargin-branch: deploy-via-build

scripts/deploy.sh

@@ -18,6 +18,7 @@ main() {
     cd "${toplevel}"
 
     sourcecred_repo=
+    static_site=
     sourcecred_site=
     preview_dir=
     trap cleanup EXIT
@@ -64,23 +65,20 @@ ensure_clean_working_tree() {
 }
 
 build_and_deploy() {
-    sourcecred_data="$(mktemp -d --suffix ".sourcecred-data")"
-    export SOURCECRED_DIRECTORY="${sourcecred_data}"
-
     sourcecred_repo="$(mktemp -d --suffix ".sourcecred-repo")"
     git clone "${SOURCECRED_REMOTE}" "${sourcecred_repo}"
     sourcecred_hash="$(
         git -C "${sourcecred_repo}" rev-parse --verify "${SOURCECRED_REF}" --
     )"
     git -C "${sourcecred_repo}" checkout --detach "${sourcecred_hash}"
-    (
-        cd "${sourcecred_repo}"
-        yarn
-        yarn backend
-        yarn build
-        node ./bin/sourcecred.js load ipfs/js-ipfs
-        node ./bin/sourcecred.js load sourcecred/sourcecred
-    )
+
+    static_site="$(mktemp -d --suffix ".static-site")"
+    "${sourcecred_repo}/scripts/build_static_site.sh" \
+        --target "${static_site}" \
+        ${DEPLOY_CNAME_URL:+--cname "${DEPLOY_CNAME_URL}"} \
+        --repo ipfs/js-ipfs \
+        --repo sourcecred/sourcecred \
+        ;
 
     sourcecred_site="$(mktemp -d --suffix ".sourcecred-site")"
     git clone "${DEPLOY_REMOTE}" "${sourcecred_site}"
@@ -95,21 +93,10 @@ build_and_deploy() {
     git -C "${sourcecred_site}" checkout --detach "${base_commit}"
     rm "${sourcecred_site}/.git/index"
     git -C "${sourcecred_site}" clean -qfdx
-    # Explode the `build/` directory into the current directory.
-    find "${sourcecred_repo}/build/" -mindepth 1 -maxdepth 1 \
+    # Explode the static site contents into the current directory.
+    find "${static_site}" -mindepth 1 -maxdepth 1 \
         \( -name .git -prune \) -o \
         -exec cp -r -t "${sourcecred_site}" -- {} +
-    # Copy the SourceCred data into the appropriate API route.
-    mkdir "${sourcecred_site}/api/"
-    mkdir "${sourcecred_site}/api/v1/"
-    cp -r "${sourcecred_data}" "${sourcecred_site}/api/v1/data"
-    if [ -n "${DEPLOY_CNAME_URL}" ]; then
-        if [ -e "${sourcecred_site}/CNAME" ]; then
-            printf 'Error: CNAME file would be overwritten!\n' >&2
-            exit 1
-        fi
-        printf '%s' "${DEPLOY_CNAME_URL}" >"${sourcecred_site}/CNAME"
-    fi
     git -C "${sourcecred_site}" add --all .
     git -C "${sourcecred_site}" commit -m "deploy-v1: ${sourcecred_hash}"
     deploy_commit="$(git -C "${sourcecred_site}" rev-parse HEAD)"
@@ -142,12 +129,15 @@ build_and_deploy() {
 }
 
 cleanup() {
-    if [ -d "${sourcecred_site}" ]; then
-        rm -rf "${sourcecred_site}"
-    fi
     if [ -d "${sourcecred_repo}" ]; then
         rm -rf "${sourcecred_repo}"
     fi
+    if [ -d "${static_site}" ]; then
+        rm -rf "${static_site}"
+    fi
+    if [ -d "${sourcecred_site}" ]; then
+        rm -rf "${sourcecred_site}"
+    fi
     if [ -d "${preview_dir}" ]; then
         rm -rf "${preview_dir}"
     fi