Add dedicated RStudio keymap

[jmcphers]

Generally speaking, we want Positron to have VS Code-like keybindings, because its heritage as a VS Code based IDE is clear (it looks like VS Code, so people will expect it to act like VS Code) and (statistically) it is more likely that new Positron users will be coming from VS Code than any other IDE.

However, we also want to honor users coming from RStudio. Towards that end, we should create an RStudio keymap that brings most of RStudio's shortcuts to Positron, removing any default VS Code bindings that conflict.

For example (noted by @DavisVaughan), in RStudio, Comment Selection is Cmd + Shift + C, but in VS Code that combination opens a new external terminal. With the RStudio Keymap activated, the RStudio behavior will take precedence.

For another example: in VS Code, Ctrl + 1 and Ctrl + 2 activate the first and second editor tabs, respectively. In RStudio, they switch between the Source and Console panes. These commands should exist in Positron, but we probably don't want to stomp on VS Code's keybindings -- unless the user has opted into RStudio compatible keymaps.

This behavior should probably not be implemented in the Positron core but instead be implemented as an RStudio keymap extension.

https://code.visualstudio.com/docs/getstarted/keybindings#_keymap-extensions

This extension should be bundled with Positron and we'll probably also want some kind of way to activate it that is more obvious than VS Code's "load keymap" command.

[jmcphers]

Another common binding the RStudio keymap could override is F1, which shows the Command Palette in VS Code but brings up Help in RStudio.

[DavisVaughan]

Option + Click and drag down for multiline cursor is also useful

[DavisVaughan]

CMD + SHIFT + T for "Run tests", as attempted in #712 but we decided not to do it there because VS Code has an existing keybinding for this combination already

[DavisVaughan]

CMD + SHIFT + N for "open a new R file" which should be easy now that we have r.createNewFile as a command

[jmcphers]

Another few based on #122 and #772:

• Cmd Shift B - Build Package (VS Code binding: Run Build Task)
• Cmd Shift L - Load Package (VS Code binding: Show Find Options)
• Cmd Shift T - Test Package (VS Code binding: Previous Editor)
• Cmd Shift E - Check Package (VS Code binding: Focus Explorer)

[juliasilge]

Plus Cmd Shift D - Document Package (VS Code binding: Show Run, i.e. workbench.view.debug)

These package development ones are probably the ones our earliest users will miss the most.

[isabelizimm]

Adding in that a pipe keybinding would be nice as well!

[DavisVaughan]

CTRL + . for some kind of "go to file / function" equivalent. Right now CMD + T will do "go to symbol in workspace" which is somewhat similar, and CMD + P will allow you to immediately type in a file name to go to

[jmcphers]

Another is Cmd Shift N, which opens a new window in VS Code but should open a new tab if RStudio bindings are active. https://positpbc.slack.com/archives/C05M2EZCPGR/p1695325876348719

[jmcphers]

Another is F2 which is Rename in VS Code but Go To Symbol in RStudio.

[juliasilge]

In Positron 2024.01.0 (Universal) build 176, I can opt in to and then use the RStudio keymap:

keymap.mov

I think as part of #1487 we should improve how this setting is surfaced in the UI because that's kind of weird/awkward: