…T endpoint on post save

…debar' into feature/2069-async-url-validation

…9-async-url-validation

…debar' into feature/2069-async-url-validation

…-url-validation

Also pass back error in REST API response to validate-post-url

…069-async-url-validation

* 'develop' of github.com:ampproject/amp-wp: (41 commits)
  Use wp_robots() instead of noindex() in WP 5.7 (#5793)
  Bump eslint-plugin-jsdoc from 31.0.3 to 31.0.4
  Bump google/cloud-storage from 1.23.0 to 1.23.1
  Update docs
  Bump stable tag to 2.0.10
  Add tests
  Restore intrinsic layout to amp-video in amp-story-page-attachment
  Use nonce scheme instead of auth scheme
  Utilize hash_equals() in unserialize_validation_error_messages()
  Fix jsdoc type as ReactElement
  Persist URL fragment through client-side mobile redirection
  Bump postcss from 8.2.2 to 8.2.4
  Bump eslint-plugin-jsdoc from 30.7.13 to 31.0.3
  Prevent infinite mobile redirect when non-AMP page served as AMP
  Remove the `class` attribute from `amp-fit-text` blocks to unblock block deprecation
  Update AMP validator spec to 8e02747, restoring intrinsic layout to amp-video
  Update validator spec to 1130
  Update amphtml spec to 2011252111002
  Bump @wordpress/compose from 3.23.0 to 3.23.1
  Bump @wordpress/block-editor from 5.2.0 to 5.2.1
  ...

…069-async-url-validation

* 'develop' of github.com:ampproject/amp-wp: (174 commits)
  Bump @wordpress/compose from 3.23.1 to 3.24.0
  Bump @wordpress/api-fetch from 3.21.1 to 3.21.2
  Wait for succss notice to appear
  Ensure "add analytics" button is in view
  Ensure `$current_screen` global variable does not interfere with tests
  Bump @wordpress/components from 12.0.1 to 12.0.2
  Bump @wordpress/browserslist-config from 2.7.0 to 3.0.0
  Bump postcss-loader from 4.1.0 to 4.2.0
  Go back to using query_var instead of query_param
  Update todo for how a condition can be updated
  Use WP_UnitTestCase for Test_AMP_Options_Manager
  Add newly-needed use statements for DependencyInjectedTestCase
  Fix test class namespaces
  Add assertion for completeness
  Rename query_var to query_param as a paired URL structure
  Use hidden prop instead of hidden class
  Change a todo into a note
  Use self instead of static
  Remove PairedUrlExamples copy pasta
  Fix since phpdoc param
  ...

The WordPress core `isDirty()` selector gets cleared only if a post gets published or updated. In case of an autosave, it still returns `true`.

In order to allow the users to revalidate AMP only if something changed since the last autosave, we had to add a custom hook that tracks the post content changes.

Once the first update is detected, a flag `isPostDirty` flag is set in the store and content is no longer checked (it's expensive since each time a content is requested, the `blocks` list must be serialized).

When the post gets saved or autosaved, the flag is cleared and the content is observed again.

…069-async-url-validation

* 'develop' of github.com:ampproject/amp-wp: (22 commits)
  Try eliminating selector based on translated string
  Fix misplacement of AMP error count in editor
  Fix phpstan static analysis failure
  Remove redundant assertion
  Update condition for checking for instance of WP_Post
  Skip ESLint report generation on PR fork; add ESLint job for PR fork
  Bump eslint-plugin-jsdoc from 31.6.0 to 31.6.1
  Bump @wordpress/browserslist-config from 3.0.0 to 3.0.1
  Bump @wordpress/block-editor from 5.2.1 to 5.2.6
  Bump @wordpress/blocks from 6.25.2 to 7.0.3
  Bump @wordpress/scripts from 13.0.1 to 13.0.3
  Bump @wordpress/hooks from 2.11.0 to 2.11.1
  Bump @wordpress/data from 4.26.2 to 4.26.6
  Add error message for the `invalid-post` error ID
  Replace `post_supports_amp` with `amp_is_post_supported`
  Update class-amp-post-type-support.php
  Update includes/class-amp-post-type-support.php
  Bump lint-staged from 10.5.3 to 10.5.4
  Bump @wordpress/edit-post from 3.26.2 to 3.26.6
  Update class-amp-post-type-support.php
  ...

…ation errors

…ewed ones

…I error handling

…dated in non-Standard mode

… endpoint