PCH Smart Linking: Implement Smart Links Reviewing step (#2507)

* Add optional `$request` parameter to `is_available_to_current_user`

* Lower phpstan type coverage param_type to 79.7

* Add Smart Linking models and bare endpoint

* Start implementing Modal UI

* Implement preview and UI elements

* Finalize modal with apply and reject actions

* Add Remove Link and Select in Editor buttons

* Backend improvements

* Improve functionality for existing smart links

* Add max-height to the sidebar

* Fix issue with the onClose callback of the modal

* Sort smart links by block position and offset

* Rebuild assets

* Rebuild assets

* Implement getting existing smart links to populate the modal

* Improve modal sidebar scrolling when navigating the smart links

* Implement retrieval of the post type for each smart link

* Improve sorting and backfilling of existing smart links data

* Better smart link detection and auto-fixing on save, link removal, and link changing.

* Move isReviewModalOpen to the store to be global across the Smart Linking component

* Add tooltip to the modal actions

* Clean-up code and documentation

* Implement the link selection functionality

* UI & functionality tweaks to the Link Details component

* Rebuild assets with the "finalized" UI & fix linting

* Rebuild assets & fix tests

* Fix some issues with link validation and saving

* Address issue with sorting in some edge cases

* Apply code review suggestions

* Apply suggestions from code review

Co-authored-by: Alex Cicovic <23142906+acicovic@users.noreply.github.com>

* Rebuild assets

* class-smart-linking-endpoint.php: Improve comments

* Fix regression with getBlockContent

* Apply suggestions from code review

Co-authored-by: Alex Cicovic <23142906+acicovic@users.noreply.github.com>

* Update src/Endpoints/class-base-endpoint.php

Co-authored-by: Alex Cicovic <23142906+acicovic@users.noreply.github.com>

* Performance improvement per code review suggestion.

* Improve comments in some PHP files

* Smart Linking Provider: Improve comments

* Apply whitespace and comment improvements

* Apply whitespace and comment improvements

* Apply comment improvements

* Rebuild assets

* Apply code review suggestions from @acicovic

* Fix tests (hopefully)

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Co-authored-by: Alex Cicovic <23142906+acicovic@users.noreply.github.com>

build/admin-settings.asset.php

@@ -1 +1 @@
-<?php return array('dependencies' => array(), 'version' => 'e15999c17e352b22474b');
+<?php return array('dependencies' => array(), 'version' => '20eafa29410328a029a2');

build/content-helper/dashboard-widget.asset.php

@@ -1 +1 @@
-<?php return array('dependencies' => array('react', 'wp-api-fetch', 'wp-components', 'wp-data', 'wp-element', 'wp-i18n', 'wp-url'), 'version' => '930369a3015a8fbd0eee');
+<?php return array('dependencies' => array('react', 'wp-api-fetch', 'wp-components', 'wp-data', 'wp-element', 'wp-i18n', 'wp-url'), 'version' => '2a085e2f1803cbb45764');