The size of the LTO build of the engine with the dylib compressed is as follows:
```sh
$ du -k libFlutter*
5236 libFlutter.dylib.tar.gz
4324 libFlutterSlimpeller.dylib.tar.gz
```
Sizes are in KiB. This represents a binary size reduction of 17.41% of the compressed artifacts. The compression ratios will likely differ based on the compression scheme.
Uncompressed, the sizes are:
```sh
$ du -k libFlutter*
16920 libFlutter.dylib
14044 libFlutterSlimpeller.dylib
```
This represents a binary size reduction of 16.99% which is in the same ballpark.
The really mucky bit was backing out the raster cache and persistent cache. I want to clean that up in a later patch so that those TUs are part of a separate submodule.
Opting out of Impeller will lead to a fatal log at startup saying the opt-out is disallowed.
Fixes https://github.com/flutter/flutter/issues/126606
Context creation options for each backend were spread across multiple
translation units. This makes setting options common across all backends hard to
configure. I have moved the creation of such common options into a separate
translation unit.
Fixes https://github.com/flutter/flutter/issues/84213
