## Description
This cleans up a lot of issues with the API doc generation.
Here are the main changes:
- Rename `dartdoc.dart` to `create_api_docs.dart`
- Move the bulk of the operations out of `dev/bots/docs.sh` into `create_api_docs.dart`.
- Delete `dashing_postprocess.dart` and `java_and_objc.dart` and incorporate those operations into `create_api_docs.dart`.
- Refactor the doc generation into more understandable classes
- Bump the snippets tool version to 0.4.0 (the latest one)
- Centralize the information gathering about the Flutter repo into the new `FlutterInformation` class.
- Clean up the directory handling, and convert to using the `file` package for all file and directory paths.
- Add an `--output` option to docs.sh that specifies the location of the output ZIP file containing the docs.
- Defaults to placing the output in `dev/docs/api_docs.zip` (i.e. where the previous code generates the file).
- Moved all document generation into a temporary folder that is removed once the documents are generated, to avoid VSCode and other IDEs trying to index the thousands of HTML and JS files in the docs output.
- Updated pubspec dependencies.
## Tests
- Added tests for doc generation.
