Fixes for background updates that break form validation for documents

[longhotsummer]

There are a couple of changes here:

• make form validation errors more obvious in the admin view, and in the logs, to trace weird validation errors that may talk about hard-to-find fields
• the above errors were caused when background tasks and images changed underneath the hood between requests. Basically they were updated/deleted and the admin form got confused. So instead, now we only show those related objects as plain HTML and not management forms
• those things happened because SourceFile was thinking that file had changed whenever it was saved, which triggered background updates. So this changes SourceFile to be opt-in to change tracking using track_changes()
• adds debug logging

[github-actions]

Test Results

32 tests   - 354   32 ✅  - 344   0s ⏱️ -26s
 7 suites  -  58    0 💤  -  10 
 7 files    -  58    0 ❌ ±  0 

Results for commit a1393d8. ± Comparison against base commit 4273083.

This pull request removes 356 and adds 2 tests. Note that renamed tests count towards both.

peachjam.tests.test_adapters.IndigoAdapterTest ‑ test_import_taxonomy_tree
peachjam.tests.test_adapters.IndigoAdapterTest ‑ test_is_responsible_for_exclude_actors
peachjam.tests.test_adapters.IndigoAdapterTest ‑ test_is_responsible_for_exclude_doctypes
peachjam.tests.test_adapters.IndigoAdapterTest ‑ test_is_responsible_for_exclude_subtypes
peachjam.tests.test_adapters.IndigoAdapterTest ‑ test_is_responsible_for_include_actors
peachjam.tests.test_adapters.IndigoAdapterTest ‑ test_is_responsible_for_include_doctypes
peachjam.tests.test_adapters.IndigoAdapterTest ‑ test_is_responsible_for_include_subtypes
peachjam.tests.test_adapters.IndigoAdapterTest ‑ test_is_responsible_for_places
peachjam.tests.test_admin.TestDocumentAdminHtmlEdit ‑ test_admin_edit_source_html_updates_content_text_and_toc
peachjam.tests.test_admin.TestJournalArticleAdmin ‑ test_add_journal_article_with_journal_and_volume
…

africanlii.tests.test_views.AfricanliiViewsTest ‑ test_homepage
africanlii.tests.test_views.AfricanliiViewsTest ‑ test_legal_instrument_listing

[github-actions]

Test Results

388 tests  +2   378 ✅ +2   23s ⏱️ -3s
 66 suites +1    10 💤 ±0 
 66 files   +1     0 ❌ ±0 

Results for commit c99925d. ± Comparison against base commit c601df8.

♻️ This comment has been updated with latest results.

[mugiwaramunyi]

Okay I understand it now....I think. A bad interaction between SourceFile's base class and the Lifecycle library, led to the weird behaviour.

Since the fix is the AttributeHooksMixin; Does this mean for classes that inherit it, they have to call track_changes() every time they want the hooks to fire, for all cases?

[longhotsummer]

Classes that use AttributeHooksMixin must call track_changes() to setup change tracking, yes. So it's opt-in.