Add read_channel_content permission (#24118)

* Add read_channel_content permission

* fix tests

* update system console default permissions per role

* add read_channel_content to e2e defaultRolesPermissions

* Migration to include custom roles

* change deprecated isNotExactRole for isNotRole

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/store/sqlstore/integrity_test.go

@@ -258,6 +258,7 @@ func createDefaultRoles(ss store.Store) {
 		DisplayName: model.ChannelUserRoleId,
 		Permissions: []string{
 			model.PermissionReadChannel.Id,
+			model.PermissionReadChannelContent.Id,
 			model.PermissionCreatePost.Id,
 		},
 	})
@@ -267,6 +268,7 @@ func createDefaultRoles(ss store.Store) {
 		DisplayName: model.ChannelGuestRoleId,
 		Permissions: []string{
 			model.PermissionReadChannel.Id,
+			model.PermissionReadChannelContent.Id,
 			model.PermissionCreatePost.Id,
 		},
 	})