SDK DAP calls setLibraryDebuggable much more than necessary

[DanTup]

There are two issues:

1. We always call setLibraryDebuggable regardless of whether the current value matches what the default would be
2. We always call setLibraryDebuggable for every library in an isolate after a Hot Reload, even though the values would stick

We should only send them if they are both a) libraries we haven't already sent values for and b) differ from what the default would be.

We need to ensure these changes don't interfere with when the user changes the settings (applyDebugOptions) which should always re-send all, or we should track the values on the VM side and then only send if they've changed.

[DanTup]

Possible fix in https://dart-review.googlesource.com/c/sdk/+/291282.

[DanTup]

Fixed by dart-lang/sdk@1112942. Needs a DDS release and to roll into Flutter.