Remove terminal detectors except the one which uses the VSCode API

[kimadeline]

There's a VS Code API that was added a while ago which we could take advantage of to figure out which shell would be launched by opening a terminal #6050 and the upstream VS Code issue microsoft/vscode#75091.

The recommendation in the vscode-python issue was to drop all of our existing shell detection mechanisms in favour of the VS Code API one, however we still have them:

vscode-python/src/client/common/serviceRegistry.ts

Lines 201 to 204 in 8661ba7

	serviceManager.addSingleton<IShellDetector>(IShellDetector, TerminalNameShellDetector);
	serviceManager.addSingleton<IShellDetector>(IShellDetector, SettingsShellDetector);
	serviceManager.addSingleton<IShellDetector>(IShellDetector, UserEnvironmentShellDetector);
	serviceManager.addSingleton<IShellDetector>(IShellDetector, VSCEnvironmentShellDetector);

➡️ Are they still necessary, all of them?

Second, shells and terminal profiles are going to change (see terminal tabs).

➡️ What does that mean for us?

[karrtikr]

Are they still necessary, all of them?

I think we only use all those classes as a fallback, in case VSCode API is unable to detect the shell (not sure if that's applicable anymore).

As mentioned here the env.shell API was already implemented in the extension microsoft/vscode#121760 (comment), but it does not seem to be working well with the new defaultProfile setting.

microsoft/vscode#121760

Related: #16175

[kimadeline]

not sure if that's applicable anymore

Yeah, that's why I think we should revisit that (and why I opened the issue), or at least investigate if they are still needed.

[druuuu]

Hi, can I work on this?

[luabud]

@druuuu because it's been a month, I'm removing you as an assignee so others can work on this if they want. If you would still like to send a PR for this issue let me know and I can add you back 😊

[karrtikr]

Except for VSCEnvironmentShellDetector, we can delete all other classes.

[luabud]

We are reserving this issue for Grace Hopper's Open Source Day, which will take place on September 22nd, 2023. If you're part of the event and would like to submit a contribution to this issue, please let us know, and we'll be happy to assign it to you.

For other community members who are not participating in the event, we appreciate your interest in contributing! We kindly request that you wait until after September 22nd to work on this issue. If no one from the event has been assigned to it by then, we'll gladly assign it to you. Thank you for your understanding and support!

[abbylt]

@luabud May I please be assigned to this issue?

[luabud]

H @abbylt, since it's been one month since OSD I'm removing you as an assignee. You can still feel free to submit a PR to this issue if you'd like, but we're going to leave it open for other contributors too.