Properly purge workspaces and clean up metadata.

Fixes #128 (closed)

Adds e2e tests to employ this purging behavior.

Examples:

Workspace to delete: test

✔ axii w purge test without active workspace

✔ axii w purge test --yes without active workspace

✔ axii w purge with workspace test active

✔ axii w purge test with another workspace active

❌ axii w purge without active workspace

❌ axii w purge test without test existing