* make intent annotations possible in TeX math items
* introduce a new command to annotate as well as node and translation
* Adds a parser expression grammar to validate intent attributes for
* it basically adds the previous, now abandoned changeset: https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Math/+/949964
Bug: T327098
Change-Id: I21adfac4c3580e238f059721fdf0c1566cb4e857
