Generate separate files for union type containers

Generating union type containers into single files (per component)
is the root cause of cyclic dependencies when we use union types
with IDL dictionaries. We should put generated containers into
separate files.

Unfortunately this CL brings a burden on developers.
See IDLUnionTypes.md for more details.

BUG=524424

CQ_INCLUDE_TRYBOTS=tryserver.chromium.win:win_optional_gpu_tests_rel;tryserver.chromium.mac:mac_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/1961883002
Cr-Commit-Position: refs/heads/master@{#393130}
131 files changed