gerrit/acl : handle submit requirements in normalise tool

This adds the keys "applicableIf" and "submittableIf" that are used by
submit-requirements [1].

[1] https://gerrit-review.googlesource.com/Documentation/config-submit-requirements.html
Change-Id: Ic4dc5877d9326897839bbe62c02c0986c6e53e25

tools/normalize_acl.py

@@ -58,11 +58,13 @@ out = ''
 
 valid_keys = {'abandon',
               'access',
+              'applicableIf',
               'create',
               'createSignedTag',
               'copyCondition',
               'defaultValue',
               'delete',
+              'description',
               'editHashtags',
               'exclusiveGroupPermissions',
               'forgeAuthor',
@@ -84,6 +86,7 @@ valid_keys = {'abandon',
               'requireContributorAgreement',
               'state',
               'submit',
+              'submittableIf',
               'toggleWipState',
               'value'}