fix(transformers): add snapshot aspects from dataset into base_transf…

[shirshanka]

…ormer

This registry was only set up for existing transformers in the code base, but fails for custom transformers written by other folks since it is not complete.

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub

[github-actions]

Unit Test Results (build & test)

  97 files  ±0    97 suites  ±0   19m 14s ⏱️ +54s
701 tests ±0  642 ✔️ ±0  59 💤 ±0  0 ❌ ±0 

Results for commit 73f1b39. ± Comparison against base commit 9e30a9c.

[github-actions]

Unit Test Results (metadata ingestion)

       5 files  ±0         5 suites  ±0   59m 11s ⏱️ - 7m 2s
   433 tests ±0     433 ✔️ ±  0    0 💤 ±  0  0 ❌ ±0 
2 090 runs  ±0  2 044 ✔️ +20  46 💤  - 20  0 ❌ ±0 

Results for commit 73f1b39. ± Comparison against base commit 9e30a9c.