* call reflection code generation from tests
This simplifies instructions to contributors so they don't forget to update
reflection code.
* add error handling to generate_code scripts
Let them propagate their errors instead of swallowing them so they show
up when called in CI.
* apply editorconfig to shell scripts
* use ordered map in dart codegen
Using an unordered map in the codegen can lead to spurious diffs in the
generated dart code.
* add CI check for generate_code being run
* update reflection_generated.h
* disable diff-check for monster_test.bfbs
Work around #5008.
(C++ only for now).
Also fixed vector of union support in the object API.
Bug: 36902939
Change-Id: I935f4cc2c303a4728e26c7916a8ec0adcd6f84cb
Tested: on Linux.
svenk177