Add command to clear extension related storage

[karrtikr]

Closes https://github.com/microsoft/vscode-python-internalbacklog/issues/151

[kimadeline]

Can you confirm the following: On the first run of the command, only the values that will be rewritten after this code gets in will get cleared? Do you have an example of such code that writes to persistent storage rarely, and would be missed on the first run of this command?

[karrtikr]

@kimadeline,

On the first run of the command, only the values that will be rewritten after this code gets in will get cleared?

You're correct, only the values that will be rewritten, or that are read will be tracked.

There can be such key values which are used (written to/read) rarely, or atleast not automatically on startup unless user triggers something. For eg. every prompt which has a "Do not show again" option, like the new workspace env prompt:

vscode-python/src/client/interpreter/virtualEnvs/virtualEnvPrompt.ts

Lines 83 to 86 in 2402acc

	const notificationPromptEnabled = this.persistentStateFactory.createWorkspacePersistentState(
	doNotDisplayPromptStateKey,
	true,
	);

But unless we track these individually, unfortunately there's no way to clear them (help VSCode!). We're assuming this is mainly for dev purposes, and we'll probably only want to clear the cache we're interacting with, in which case this command should be useful.