Add custom methods to the workspace adapter

[amstilp]

Add new methods to the workspace adapter that can run custom code when a user performs specific actions:

• before_workspace_create: run before a workspace is created on AnVIL
• after_workspace_create: run after a workspace is created on AnVIL
• after_workspace_import: run before a workspace is imported on AnVIL

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.74%. Comparing base (9ccd445) to head (cd6ea59).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #499 +/- ## ======================================== Coverage 99.74% 99.74% ======================================== Files 130 131 +1 Lines 23857 23959 +102 ======================================== + Hits 23795 23897 +102 Misses 62 62 ```

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