feat(mentions,tags): tag mentions (#3769)

* feat: add tag search

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* feat(mentions): tag mentions backend

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* feat: tag mention design

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* refactor: revamp mentions autocomplete

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* fix: unauthorized mention of hidden groups

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* feat(mentions,tags): use hash format for tag mentions

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* refactor: frontend mention format API with mentionable models

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* feat: implement tag search on the frontend

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* fix: tag color contrast

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* fix: tag suggestions styling

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* test: works with disabled tags extension

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* chore: move `MentionFormats` to `formats`

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* fix: mentions preview bad styling

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* docs: further migration location clarification

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* Apply fixes from StyleCI

* fix: bad test namespace

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* fix: phpstan

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* fix: conditionally add tag related extenders

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* Apply fixes from StyleCI

* feat(phpstan): evaluate conditional extenders

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

* feat: use mithril routing for tag mentions

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>

---------

Signed-off-by: Sami Mazouz <sychocouldy@gmail.com>
Co-authored-by: StyleCI Bot <bot@styleci.io>

extensions/mentions/composer.json

@@ -33,6 +33,9 @@
         "flarum-extension": {
             "title": "Mentions",
             "category": "feature",
+            "optional-dependencies": [
+                "flarum/tags"
+            ],
             "icon": {
                 "name": "fas fa-at",
                 "backgroundColor": "#539EC1",
@@ -74,6 +77,7 @@
     },
     "require-dev": {
         "flarum/core": "*@dev",
+        "flarum/tags": "*@dev",
         "flarum/testing": "^1.0.0"
     },
     "repositories": [