This does a cleanup of the examples, removing all of the "section" markers and extra comments that we don't need anymore now that the samples are no longer in the source code. It also removes the --template arguments from the {@tool dartpad} and {@tool sample} directives, since those are no longer used. It converts two examples that I discovered were still embedded into linked examples in the examples folder.

I didn't delete the templates from the snippets config folder yet, because there are still embedded samples in the dart:ui package from the engine that use them. Once dart:ui no longer uses the templates, they can be removed.

I bumped the version of the snippets package to pick up a change that allows removal of the --template argument.

This extracts the sample code out from the API doc comments, and places them in separate files on disk, allowing running of the examples locally, testing them, and building of slightly larger examples.

This reverts commit d056500b.

This reverts commit 31de052e.

This reverts commit e2490f29.

Applies #78522 to existing code, by replacing all occurrences of LogicalKeySet to SingleActivator or ShortcutActivator.

Update samples to use repo analysis options, Fix sample templates and a ton of analyzer issues (#77868)

This removes the nullOk parameter from Actions.invoke, and adds an Actions.maybeInvoke function. The difference is that invoke will now always (in debug mode) throw if an enabled action isn't found, and maybeInvoke will return null if an enabled action isn't found. The invoke function can still return null as the result of the invocation, though, so I purposely didn't change the return value to Object from Object?.

Adds a couple of new examples to the Actions and Shortcuts widgets, and updates some documentation.

Adds an example to the docs for ActionListener.

Change the semantics of Actions.invoke so that if the action it finds is disabled, then it keeps looking for an ancestor Actions widgets that has a matching intent where the action is not disabled.