fix: always show Add to Workspace button on repositories table

[brandonroberts]

Description

• Always displays Add to Workspace button in repositories table
• Logs a Posthog event when the button is clicked with the workspaceId and selected repositories.

Related Tickets & Documents

Mobile & Desktop Screenshots/Recordings

Steps to QA

1. Go to explore page
2. Note Add to Workspace is disabled
3. Select some repositories
4. Note Add to Workspace is enabled
5. Click button and navigate to new workspace page with repos selected

Tier (staff will fill in)

• [ ] Tier 1
• [ ] Tier 2
• [ ] Tier 3
• [x] Tier 4

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