add a button to clear out finished share links

The dashboard listed every share ever made, including ones revoked or expired
months ago, and nothing ever pruned them. There is now a "Clean up finished links"
button next to Refresh that runs a normal cleanup pass and then drops the records
that are done with, reporting how many went.

Only revoked, expired and failed records are removed. A link that can still be
used is left alone, including a spent one-use link whose guest is still watching
until it expires, since that record is Redeemed rather than finished.

Folded into 1.0.3.0 rather than shipped as 1.0.3.1: the ceiling fix and this are
going out as one replacement of that version.

Jellyfin.Plugin.ShareLinks/Jellyfin.Plugin.ShareLinks.csproj

@@ -6,9 +6,9 @@
     <LangVersion>latest</LangVersion>
     <RootNamespace>Jellyfin.Plugin.ShareLinks</RootNamespace>
     <AssemblyName>Jellyfin.Plugin.ShareLinks</AssemblyName>
-    <Version>1.0.3.1</Version>
-    <AssemblyVersion>1.0.3.1</AssemblyVersion>
-    <FileVersion>1.0.3.1</FileVersion>
+    <Version>1.0.3.0</Version>
+    <AssemblyVersion>1.0.3.0</AssemblyVersion>
+    <FileVersion>1.0.3.0</FileVersion>
     <GenerateAssemblyInfo>true</GenerateAssemblyInfo>
     <TreatWarningsAsErrors>false</TreatWarningsAsErrors>
     <ImplicitUsings>disable</ImplicitUsings>