Relands #126086, which was reverted by #126569.

Reverts flutter/flutter#126086.

This PR changed the interfaces of some classes, namely `AndroidSdk`, and deleted a global.

These classes had custom overrides in g3 that were not updated with a g3fix, so this PR has broken tests. See https://b.corp.google.com/issues/281945232 (non-public link)

This is the first step in unifying Java-finding logic across the tool. If curious, see #126029 for an example of what all the changes will probably entail.

Moves java-related functionality like `AndroidSdk.findJavaHome` to a new class, `Java`.

See tracking issue https://github.com/flutter/flutter/issues/126126 for more.

Update device selection to wait for wireless devices to load

Update device filtering and introduce isConnected and connectionInterface

This reverts commit 275ab9c6.

Revert "Reland "Remove references to Observatory (#118577)""

This reverts commit 298d8c76.

This reverts commit 2df140f4.

Observatory is being deprecated for Dart 3.0 so it should no longer be
referenced in tooling messaging / flags.

See https://github.com/dart-lang/sdk/issues/50233

* Migrate packages/flutter_tools/test/commands.shard/hermetic, part 3/3

* Fix tests

* Chris's comment

Also allow daemon commands to pass binary streams