Sets a minimal baseline version for IDEs to verify a hot-reload supporting SDK.

Fixes: https://github.com/flutter/flutter-intellij/issues/293

* cleanup obtaining user home directory path
* refactor doctor and detect IntelliJ on Mac
* fix detect Flutter plugin for IntelliJ

* Switch to using PlatformPlugin instead of mojom

* Update engine.version

These changes were generated by IntelliJ.

The Skia team tells us that these go faster.

Previously, overall status was reported as good if Xcode and homebrew
were installed, even if there were issues with either of the tools. We
now report partial status if we detect issues with either installation.

This wrapper will eventually replace HostMessages.

Picks up a patched `dartdoc` (effecting, notablly, `crossdart`…)

We were missing these before.

This match switches the framework to use the semantics backend in `dart:ui`
rather than the Mojo backend.

This example is misleading because it relies on the old services model.
Let's remove it until #6263 is fixed.

Instead of reading the mojom serialization and re-inflating it, the
SemanticsDebugger now shows the SemanticsNode objects directly.

Performance improvement for https://github.com/flutter/flutter/issues/6008

This patch adds `@checked` everywhere is needed to remove the
`strong_mode_invalid_method_override` strong mode error.

* commit intellij project metadata

* move metadata to the top level

* delete dev/intellij

The only change here is that if we run off the end of the loop in a way
that previously would have just hung, we return silently.

This will make it easier to switch to SemanticsUpdateBuilder.

This change might make our grammar less perfect, but it will increase our
sanity.

Fixes https://github.com/flutter/flutter/issues/5763

RC1 patch release.