Bug 1952878 - Use libs.versions.ktlint for ktlint version of geckoview. r=geckoview-reviewers,calu

Actually, GeckoView's ktlint version is hard coded. But Fenix and AC
define it into `libs.versions.toml`. So we should use same file since we
use same version.

Differential Revision: https://phabricator.services.mozilla.com/D240859

build.gradle

@@ -499,7 +499,7 @@ subprojects { project ->
                     include '**/*.kt'
                     exclude '**/thirdparty/**'
                 }
-                ktlint('0.49.1')
+                ktlint("${libs.versions.ktlint.get()}")
             }
         }
     }