wxGUI/lmgr: add menu item for launching dialog for setting RStudio path

[tmszi]

Implement (fixes) issue #1171.

Set RStudio path interactively from wxGUI Layer Manager menu (dialog):

[wenzeslaus]

+1 in general. We need some "integrated/related tools" concept in the GUI or in general. For example, we have some code for integrating with ISIS which is partially in grass.py and partially you do some manual hacking. On Windows, we try to work with R and RStudio and external Python editors with some Windows-specific scripting. ...

Looking at the new state of that menu, this PR raises priority of moving the mapset stuff out of there million times. @petrasovaa @lindakladivova

[ninsbl]

Bumping up milestone as 8.0.1 is due in two days, while this has not been part of RC1 and there has not been activity for some time.

[neteler]

This PR needs to be rebased.

[hellik]

see also #3091 winGRASS and R integration/coupling

[neteler]

@tmszi Would you be willing to resolve the merge conflicts in this PR?

[github-actions]

[ruff] _{reported by reviewdog 🐶}

Suggested change

GListCtrl,