Dev: register command to clear Cody storages

[abeatrix]

Add a new command to make it easier for Devs (currently in dev and test mode only) to clear current auth states and storages for debugging purpose.

• Add a new command "cody.dev.clear" to remove the current access token, remove all stored access tokens, clear the local storage, and restart VS Code
• Change the local storage key used to suppress Cody Pro expiration notifications
• Refactor the local storage provider to use a centralized key map
• Add a clear method to the local storage provider to easily clear all stored data except the anonymous user ID
• Update the LocalStorageProvider to add a new key for the access token secret
• Update the SecretStorageProvider to use the new access token secret key from the LocalStorageProvider
• Remove the code to clear the storage and access token in the post-uninstall script, as this is now handled by the new "cody.dev.clear" command

Currently available in Dev & Test mode only.

Test plan

1. Start Cody from this branch to make sure Chat history and Auth are still working as expected.
2. Run the new command Cody Dev: Clear Cody Storage & Restart to verify you have been logged out
3. Verify chat history and endpoint history are cleared after logging back in