Summary:
@public
Previously, all ConcreteShadowNode subclasses had to override `getComponentName()` function to specialize a name of the component. And often it was all that those subclasses do. Now, it's a template argument; and many ShadowNode classes can be created as oneliners via *just* specializing ConcreteShadowNode template.
Unfortunately, C++ does not allow to use `std::string`s or string literals as template arguments, but it allows to use pointers. Moreover, those pointers must point to some linked data, hence, those values must be declared in .cpp (not .h) files. For simplicity, we put those constants in Props classes, (but this is not a strong requirement).
Reviewed By: mdvacca
Differential Revision: D8942826
fbshipit-source-id: 4fd517e2485eb8f8c20a51df9b3496941856d8a5
67a79010ca