feature #13025 [Notifier] Added Notifier guide (TheGarious, andreybolonin, savvasal, wouterj)

This PR was merged into the 5.0 branch.

Discussion
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[Notifier] Added Notifier guide

This PR merges the work of our doc hero's @TheGarious, @andreybolonin and @savvasal in #12678, #12846 and #12963 .

Fixes #12430 and fixes #12552

The component has 2 different usages: Using the high-level Notifier abstraction and using the lower-level Chatter and Texter abstractions. I decided to only document the high-lever in the main guide and use sub guides for Chatter and Texter.

This PR focuses on having the base documentation ready. Some features (monolog & messenger integration) are not documented. Let's create issues for those and do them after this PR is merged.

Commits
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69f3330 Improved some grammar thanks to @savvasal
06f7009 Add Notifier component documentation
0179303 Reorder the use statements alphabetically
b9d0d7f Slack notifier actions documentation
34f23d0 add notifier.rst
4810fbf WIP Notifer Page

Author: OskarStark

_build/redirection_map

@@ -479,3 +479,4 @@
 /components/translation/usage /translation
 /components/translation/custom_formats https://github.com/symfony/translation
 /components/translation/custom_message_formatter https://github.com/symfony/translation
+/components/notifier https://github.com/symfony/notifier

components/notifier.rst

@@ -47,6 +47,7 @@ Topics
     mercure
     messenger
     migration
+    notifier
     performance
     profiler
     routing

index.rst

@@ -12,6 +12,9 @@ integration, CSS inlining, file attachments and a lot more. Get them installed w
 
     $ composer require symfony/mailer
 
+
+.. _mailer-transport-setup:
+
 Transport Setup
 ---------------