flutter_tool: DeferredComponent and LoadingUnit classes, Manifest deferred-components parsing (#75394)

This reverts commit 8b6baae4.

Our current top crasher is an unclear error when ProcessManager fails to resolve an executable path. To fix this, we'd like to being adjusting the process resolution logic and adding more instrumentation to track failures. In order to begin the process, the ProcessManager has been folded back into the flutter tool

= gets escaped into %3D which seems to be tripping up cmake on windows since % is a control character. Switch to base64 encoding, since this does not have % nor , in the output character set.

This change is not trivially cherry pickable, and isn't tested on windows aside from my local, manual tests due to the planned CI work not being complete yet.

Fixes #75017
Fixes #74705

This reverts commit 547ed88a.

* opt out the flutter tool

* oops EOF

* fix import

* Update tool_backend.dart

* Update daemon_client.dart

* fix more

* Reorganize files

* Use l10n.yaml instead of command line args

In principle this is backwards compatible; I just merged all the classes into one and deprecated everything that became redundant as a result.

This reverts commit 8749d955.

In principle this is backwards compatible; I just merged all the classes into one and deprecated everything that became redundant as a result.