Add anonymous access support for private/unlisted repositories (#34051)

Follow #33127

Fix #8649, fix #639

This is a complete solution. A repo unit could be set to:

* Anonymous read (non-signed-in user)
* Everyone read (signed-in user)
* Everyone write (wiki-only)

options/locale/locale_en-US.ini

@@ -926,6 +926,9 @@ permission_not_set = Not set
 permission_no_access = No Access
 permission_read = Read
 permission_write = Read and Write
+permission_anonymous_read = Anonymous Read
+permission_everyone_read = Everyone Read
+permission_everyone_write = Everyone Write
 access_token_desc = Selected token permissions limit authorization only to the corresponding <a %s>API</a> routes. Read the <a %s>documentation</a> for more information.
 at_least_one_permission = You must select at least one permission to create a token
 permissions_list = Permissions:
@@ -1138,6 +1141,7 @@ transfer.no_permission_to_reject = You do not have permission to reject this tra
 
 desc.private = Private
 desc.public = Public
+desc.public_access = Public Access
 desc.template = Template
 desc.internal = Internal
 desc.archived = Archived
@@ -2133,6 +2137,7 @@ contributors.contribution_type.deletions = Deletions
 settings = Settings
 settings.desc = Settings is where you can manage the settings for the repository
 settings.options = Repository
+settings.public_access = Public Access
 settings.collaboration = Collaborators
 settings.collaboration.admin = Administrator
 settings.collaboration.write = Write
@@ -2179,7 +2184,6 @@ settings.advanced_settings = Advanced Settings
 settings.wiki_desc = Enable Repository Wiki
 settings.use_internal_wiki = Use Built-In Wiki
 settings.default_wiki_branch_name = Default Wiki Branch Name
-settings.default_permission_everyone_access = Default access permission for all signed-in users:
 settings.failed_to_change_default_wiki_branch = Failed to change the default wiki branch.
 settings.use_external_wiki = Use External Wiki
 settings.external_wiki_url = External Wiki URL