Option to Archive Conversation on PR Comments

Description

Currently when a conversation is listed in the comments tab of the panel, the only action available is to resolve conversation, by clicking the checkmark symbol.

This feature request is about enabling another option which archives said conversation. This means hiding the conversation unless the conversation evolves (i.e. there are new replies).

It is intended to help PR assignees better manage PR conversations, with side-effects helping reviewers to facilitate conversations that may require further follow-up:

• As an assignee, if I resolve the conversation, it would be tedious for the reviewer to follow-up upon a concern if necessary.
• If an assignee, replies on a conversation and are now awaiting for a response, they are effectively blocked. If multiple conversations are opened, having this blocked conversation lingering can be frustrating to the assignee while going through other conversations.

Appendix - Motivation

This feature is inspired by most email clients where there is an archive folder as opposed to an inbox:

• New, active mail chain responses goes to inbox
• Stale/blocked mail chains go to archive
• Complete conversations either go to archive or deleted (depending on how relevant they might be in the future)

Suggested Solution

• Add an archive button to each PR conversation in the Comments Panel (consider same symbolic icon used for archive in email)
• When a conversation is archived hide it from the user, keeping track of its status in the local application
• Should a reply come through, restore visibility to said conversation
• As a failsafe, just in case the system is struggling to identify if the conversation has changed, opt to have it revealed, rather than archived (let the user handle it, even if slightly pedantic)
• Have an option to reveal archived conversations (maybe appended to existing conversations, or under a subpanel - tbd...)

Start by tracing the pull-request Comments Panel and how it currently resolves conversations. Define how archived state is stored locally, how replies restore visibility, and where a control for revealing archived conversations belongs. Done means archived conversations are hidden, new replies reveal them, and users can view archived conversations when needed.