Individual icons for each panel

**Describe the bug**
The panel icons for Jira issues, BitBucket PRs and BitBucket Pipelines are identical (the Atlassian logo), which makes it difficult to identify the correct panel without going through all of them.

**To Reproduce**
Steps to reproduce the behavior:
1. Move all the panels to a separate view

**Expected behavior**
I would expect the Jira panel to have the Jira logo, while the PRs and Pipelines panels should each have the logo (or a similar one) that they have within BitBucket web UI.

**Screenshots**

**Environment and Version (please complete the following information):**
- Atlassian Plugin Version (3.8.5)
- Visual Studio Code Version (1.101.2)
- Is this a local or cloud environment? (???)
- If Cloud, Browser (n/a)
- If Local, OS (macOS)

**Additional context**
n/a

No source files or tests are named. Start by locating the VS Code panel registrations and icon definitions for Jira issues, Bitbucket pull requests, and Bitbucket Pipelines, then check how their existing Atlassian icons are selected. Done means each panel has a distinct icon matching the requested Jira, PR, and Pipelines identities.

Written by the indexing model from the issue text.