This adds a new field into `xsbti.Problem` allowing for the compiler to
forward "actions" that can address diagnostics. The idea largely mimics
a very minimal `CodeAction` that can be found in the [LSP
Spec](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#codeAction)
in order to ensure it will work with a variety of difference clients
that use LSP, and those that don't. In the future the `WorkspaceEdit`
that was created here could also be expanded to handle more advanced
changes, aka resource operations, like creating/moving/deleting files.
For now we only focus on a small subset of these features.
Chris Kipp