## Description
This improves defaults generation with logging, stats, and token validation.
This PR includes these changes:
* introduce `TokenLogger`, with a verbose mode
* prints versions and tokens usage to the console
* outputs `generated/used_tokens.csv`, a list of all used tokens, for use by Google
* find token files in `data` automatically
* hide tokens `Map`
* tokens can be obtained using existing resolvers (e.g. `color`, `shape`), or directly through `getToken`.
* tokens can be checked for existence with `tokenAvailable`
* remove version from template, since the tokens are aggregated and multiple versions are possible (as is the case currently), it does not make sense to attribute a single version
* improve documentation
## Related Issues
- Fixes https://github.com/flutter/flutter/issues/122602
## Tests
- Added tests for `TokenLogger`
- Regenerated tokens, no-op except version removal
## Future work
A future PR should replace or remove the following invalid tokens usages
<img width="578" alt="image" src="https://github.com/flutter/flutter/assets/6655696/b6f9e5a7-523f-4f72-94f9-1b0bf4cc9f00">
* Revert "Revert "Add Material 3 support for BottomAppBar" (#114421)"
This reverts commit 210a2aa371.
* Regenerated the defaults from tokens and fixed tests.
* Fixed the tests.
* Updated the shape token template to optimize the a common case.
