Add settings to control the icons used in Issues and PR tree views

[kabel]

Implements the feature request #6641.

Both tree views support an icon mode of author (default), state, or generic.

author follows the existing logic prior to this setting, where we attempt to fetch a rounded avatar. PRs fall back to a GitHub icon and Issues fall back to state-specific icon.

state will always use a state-specific icon that matches the Issue/PR type and state.

generic will always use the GitHub icon for a PR and an uncolored issues theme icon for Issues.

[kabel]

Example render screenshots:

PR mode state:

Issues mode state:

PR mode generic:

Issues mode generic:

[alexr00]

Thanks for the PR @kabel. What is the benefit of having the generic option?

[kabel]

What is the benefit of having the generic option?

I don't have a compelling reason. A few thoughts being:

• More user choice for interface items pique end-users interest
• Gives an alternative style for users that prefer to avoid avatar network requests (all hail :octocat:)
• Provides a colorless option for users that want to minimize interface distractions/colors

[alexr00]

Thanks for your patience on this. I'm planning to review it on Friday when we open our main branch back up for August changes.

[alexr00]

@copilot I have sadly neglected this PR, which adds two settings for controlling which icon shows for view tree items: one setting for PRs and the other for issues. In the time since this PR was created, a setting was added which covers part of the feature for issues, but it's missing the state and generic options. Please do the following:

• Bring the branch up to date with main
• Update githubIssues.issueAvatarDisplay to include state and generic as currently implemented in this PR
• Rename the githubPullRequests.treeViewIconMode to githubPullRequests.pullRequestAvatarDisplay