Feature: Share links (#3996)

* Implement share links

Basic implementation of share links

Make certain share link fields not editable, automatically grant permissions on migrate

Updated styling, error messages from expired / deleted links

frontend code linting, reversable sharelink migration

testing coverage

Update translation strings

No links message

* Consolidate file response methods

* improvements to share links on mobile devices

* Refactor share links file_version

* Add docs for share links

* Apply suggestions from code review

* When filtering share links, use the timezone aware now()

* Removes extra call to setup directories for usage in testing

* FIx copied badge display on some browsers

* Move copy to ngx-clipboard library

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Co-authored-by: Trenton H <797416+stumpylog@users.noreply.github.com>

docs/usage.md

@@ -545,3 +545,16 @@ Paperless-ngx consists of the following components:
 
 - Optional: A database server. Paperless supports PostgreSQL, MariaDB
   and SQLite for storing its data.
+
+## Share Links
+
+Paperless-ngx added the abiltiy to create shareable links to files in version 2.0. You can find the button for this on the document detail screen.
+
+- Share links do not require a user to login and thus link directly to a file.
+- Links are unique and are of the form `{paperless-url}/share/{randomly-generated-slug}`.
+- Links can optionally have an expiration time set.
+- After a link expires or is deleted users will be redirected to the regular paperless-ngx login.
+
+!!! tip
+
+    If your paperless-ngx instance is behind a reverse-proxy you may want to create an exception to bypass any authentication layers that are part of your setup in order to make links truly publicly-accessible. Of course, do so with caution.