IndieAuth support (#1811)

* Able to authenticate user against IndieAuth. For #1273

* WIP server indieauth endpoint. For https://github.com/owncast/owncast/issues/1272

* Add migration to remove access tokens from user

* Add authenticated bool to user for display purposes

* Add indieauth modal and auth flair to display names. For #1273

* Validate URLs and display errors

* Renames, cleanups

* Handle relative auth endpoint paths. Add error handling for missing redirects.

* Disallow using display names in use by registered users. Closes #1810

* Verify code verifier via code challenge on callback

* Use relative path to authorization_endpoint

* Post-rebase fixes

* Use a timestamp instead of a bool for authenticated

* Propertly handle and display error in modal

* Use auth'ed timestamp to derive authenticated flag to display in chat

* don't redirect unless a URL is present

avoids redirecting to `undefined` if there was an error

* improve error message if owncast server URL isn't set

* fix IndieAuth PKCE implementation

use SHA256 instead of SHA1, generates a longer code verifier (must be 43-128 chars long), fixes URL-safe SHA256 encoding

* return real profile data for IndieAuth response

* check the code verifier in the IndieAuth server

* Linting

* Add new chat settings modal anad split up indieauth ui

* Remove logging error

* Update the IndieAuth modal UI. For #1273

* Add IndieAuth repsonse error checking

* Disable IndieAuth client if server URL is not set.

* Add explicit error messages for specific error types

* Fix bad logic

* Return OAuth-keyed error responses for indieauth server

* Display IndieAuth error in plain text with link to return to main page

* Remove redundant check

* Add additional detail to error

* Hide IndieAuth details behind disclosure details

* Break out migration into two steps because some people have been runing dev in production

* Add auth option to user dropdown

Co-authored-by: Aaron Parecki <aaron@parecki.com>

static/metadata.html.tmpl

@@ -49,6 +49,8 @@
   <link rel="icon" type="image/png" sizes="16x16" href="/img/favicon/favicon-16x16.png">
   <link rel="manifest" href="/manifest.json">
 
+  <link rel="authorization_endpoint" href="/api/auth/provider/indieauth">
+
   <meta name="msapplication-TileColor" content="#ffffff">
   <meta name="msapplication-TileImage" content="/img/favicon/ms-icon-144x144.png">
   <meta name="theme-color" content="#ffffff">