feat(lsp): jupyter notebook analysis

[nayeemrmn]

All of our analysis and editor features will work in vscode notebook cells with this.

About 5/6 of this PR is making sure we re-normalize module specifiers that come out of tsc, since notebook cell URIs have to be transformed on the way in.

Coupled with denoland/vscode_deno#949.
Fixes #20657.
Fixes .. #20662.

Todo (not in this PR):

• Local variables aren't remembered between cells. They're essentially different modules.
  Ref: Jupyter kernel on vscode gives error about variables declared on above cells vscode_deno#932.

[rgbkrk]

This doesn't close #20662, as that's for supporting the extended Jupyter protocol completions (separate from LSP) when attached to a Jupyter Frontend (Jupyterlab, jupyter console).

Awesome to see for us VS Code users though! Thank you.

[nayeemrmn]

• Local variables aren't remembered between cells. They're essentially different modules.

Interesting update! It seems the regular node/ts server does the same thing, for each cell that contains import or export. It just tries to keep the rest in script mode. But even then it doesn't validate the ordering at all.

With that in mind I think this is ready to land as an MVP.

[nayeemrmn]

• Sometimes you get a silent tsc error because the cell URLs don't end with a .ts extension. We have a specifier denormalization layer for that but it's tricky because we currently don't normalize everywhere we should, and it needs to take into account the out-of-band media type provided with textDocument/didOpen.

Done now: 3d5e434. This normalizes all module specifiers that come out of tsc, and denormalizes notebook cell specifiers that go into tsc (by converting them to file URLs and forcing a file extension).

This basically has parity with modules now. All quick-fixes, local and remote import completion, auto-imports etc. work as far as I can see. It's in a pretty complete state apart from:

• Local variables aren't remembered between cells. They're essentially different modules.

which is the same case with the node/tsc server.

[dsherret]

LGTM!