Improve field query and fix mariadb's pickiness with parens

If no query is given, don't search with `like '%'`. MariaDB doesn't
want parens around columns in the GROUP BY clause.

modules/store/src/main/scala/docspell/store/impl/DoobieSyntax.scala

@@ -13,7 +13,7 @@ trait DoobieSyntax {
     groupBy(NonEmptyList.of(c0, cs: _*))
 
   def groupBy(cs: NonEmptyList[Column]): Fragment =
-    fr" GROUP BY (" ++ commas(cs.toList.map(_.f)) ++ fr")"
+    fr" GROUP BY " ++ commas(cs.toList.map(_.f))
 
   def coalesce(f0: Fragment, fs: Fragment*): Fragment =
     sql" coalesce(" ++ commas(f0 :: fs.toList) ++ sql") "

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

@@ -42,7 +42,7 @@ object QCustomField {
 
     val nameCond = nameQuery.map(QueryWildcard.apply) match {
       case Some(q) =>
-        or(fName.lowerLike(q), fLabel.lowerLike(q))
+        or(fName.lowerLike(q), and(fLabel.isNotNull, fLabel.lowerLike(q)))
       case None =>
         Fragment.empty
     }

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

@@ -11,7 +11,9 @@ object QueryWildcard {
       if (n.endsWith("*")) s"${n.dropRight(1)}%"
       else n
 
-    prefix(suffix(value))
+    val res = prefix(suffix(value))
+    if (res == "%%") "%"
+    else res
   }
 
 }

modules/store/src/test/scala/docspell/store/queries/QueryWildcardTest.scala

@@ -18,4 +18,9 @@ object QueryWildcardTest extends SimpleTestSuite {
     assertEquals("%name%", QueryWildcard("*name*"))
     assertEquals("%some other name%", QueryWildcard("*some other name*"))
   }
+
+  test("do not use multiple wildcards") {
+    assertEquals("%", QueryWildcard("**"))
+    assertEquals("%*%", QueryWildcard("***"))
+  }
 }