Provide endpoints to submit tasks to re-generate previews

The scaling factor can be given in the config file. When this changes,
images can be regenerated via POSTing to certain endpoints. It is
possible to regenerate just one attachment preview or all within a
collective.

modules/store/src/main/scala/docspell/store/queries/QAttachment.scala

@@ -26,9 +26,9 @@ object QAttachment {
     Stream
       .evalSeq(store.transact(findPreview))
       .map(_.fileId.id)
+      .evalTap(_ => store.transact(RAttachmentPreview.delete(attachId)))
       .flatMap(store.bitpeace.delete)
       .map(flag => if (flag) 1 else 0)
-      .evalMap(_ => store.transact(RAttachmentPreview.delete(attachId)))
       .compile
       .foldMonoid
   }

modules/store/src/main/scala/docspell/store/records/RAttachment.scala

@@ -231,6 +231,30 @@ object RAttachment {
   def findItemId(attachId: Ident): ConnectionIO[Option[Ident]] =
     selectSimple(Seq(itemId), table, id.is(attachId)).query[Ident].option
 
+  def findAll(
+      coll: Option[Ident],
+      chunkSize: Int
+  ): Stream[ConnectionIO, RAttachment] = {
+    val aItem = Columns.itemId.prefix("a")
+    val iId   = RItem.Columns.id.prefix("i")
+    val iColl = RItem.Columns.cid.prefix("i")
+
+    val cols = all.map(_.prefix("a"))
+
+    coll match {
+      case Some(cid) =>
+        val join = table ++ fr"a INNER JOIN" ++ RItem.table ++ fr"i ON" ++ iId.is(aItem)
+        val cond = iColl.is(cid)
+        selectSimple(cols, join, cond)
+          .query[RAttachment]
+          .streamWithChunkSize(chunkSize)
+      case None =>
+        selectSimple(cols, table, Fragment.empty)
+          .query[RAttachment]
+          .streamWithChunkSize(chunkSize)
+    }
+  }
+
   def findWithoutPreview(
       coll: Option[Ident],
       chunkSize: Int