Various refactorings

[jwortmann]

These are a bunch of minor refactorings that I wanted to do. Most of it just moves some code to other places where it makes more sense, but there are no functional changes. See the individual commits for details.

Everything touched by this PR should just be internal functions and constants, so I believe it should be safe to do. At some time the public API for LSP-* packages in LSP/plugin/__init__.py should probably be revised and extended, because various packages already import utility functions directly from LSP/plugin/core/views.py.

To be released together with:

• adapt to changes in LSP 1.27.0 LSP-volar#212
• Update import paths LSP-jdtls#44

[rchl]

Those broke for me:

https://github.com/sublimelsp/LSP-jdtls/blob/6a0041c7e8ccffe2f77cdc924e3e1a362a3028c8/modules/test_extension_commands.py#L9-L11

https://github.com/sublimelsp/LSP-volar/blob/70ccf1c86258f54932be07babead4c91308e3e53/volar_virtual_file_hierarchy.py#L7-L7

[jwortmann]

Oh wow, I didn't know that you used the TreeView somewhere else. That is cool.

The reason I initially put new_tree_view_sheet into core/registry.py was only to avoid cyclic imports which I didn't know how to fix differently at that time. But I think it would be cleaner code now with the TYPE_CHECKING approach that I used in this PR, and then we could just update the import in LSP-volar?

And I could do a PR to update the imports in LSP-jdtls with the next LSP release. I guess that would be easier than to leave behind some aliases to those constants in views.py for backwards compatibility.

[rchl]

Yeah, new paths are nicer. Only that we should make sure to update those and do a synced release.

[rchl]

Created sublimelsp/LSP-volar#212

[rchl]

Looks like this needs to be rebased to be be able to use "reabse and merge" strategy.