[Enhancement] Allow forcing a refresh of source metadata (#194)

* Stopped sources from fetching metadata on every update

* Added action button to force a metadata refresh

lib/pinchflat_web/controllers/sources/source_html/actions_dropdown.html.heex

@@ -30,6 +30,15 @@
       Force Index
     </.link>
   </:option>
+  <:option>
+    <.link
+      href={~p"/sources/#{@source}/force_metadata_refresh"}
+      method="post"
+      data-confirm="Are you sure you want to refresh this source's metadata?"
+    >
+      Refresh Metadata
+    </.link>
+  </:option>
   <:option>
     <div class="h-px w-full bg-bodydark2"></div>
   </:option>

lib/pinchflat_web/controllers/sources/source_html/source_form.html.heex

@@ -23,7 +23,7 @@
       field={f[:custom_name]}
       type="text"
       label="Custom Name"
-      help="Something descriptive. Does not impact indexing or downloading"
+      help="Does not impact indexing or downloading. Will be inferred from the source if left blank"
     />
 
     <.input field={f[:original_url]} type="text" label="Source URL" help="URL of a channel or playlist (required)" />
@@ -111,7 +111,8 @@
         type="text"
         label="Title Filter Regex"
         placeholder="(?i)^How to Bike$"
-        help="A PCRE-compatible regex. Only media with titles that match this regex will be downloaded. Look up 'SQLean Regex docs' for more"
+        help={title_filter_regex_help()}
+        html_help={true}
       />
 
       <section