Bug 1859434 - ignore GeckoView directory with generated .class files r=geckoview-reviewers,m_kato DONTBUILD

This directory is generated during builds and contains generated .class files for the annotation processor. These should not be checked into the repository.

Differential Revision: https://phabricator.services.mozilla.com/D191148

.hgignore

@@ -297,3 +297,6 @@ gfx/wr/target/
 
 # Ignore automatically generated mots documentation
 ^docs/mots/index.rst
+
+# Ignore generated directory with .class files for GeckoView annotation processor
+^mobile/android/annotations/bin/