fix(docx): fix OMML equation handling and improve type safety (#3381)

* fix(docx): handle missing chr attribute in groupChr OMML elements

Signed-off-by: Cesar Berrospi Ramis <ceb@zurich.ibm.com>

* fix(docx): escape spaces in OMML limit text for proper LaTeX rendering

Signed-off-by: Cesar Berrospi Ramis <ceb@zurich.ibm.com>

* fix(docx): fix inline equation reconstruction to prevent tag corruption

Signed-off-by: Cesar Berrospi Ramis <ceb@zurich.ibm.com>

* chore(docx): add type hints and docstrings to OMML module

Signed-off-by: Cesar Berrospi Ramis <ceb@zurich.ibm.com>

* fix(docx): fix genfrac formatting and eliminate grouping function warnings

Signed-off-by: Cesar Berrospi Ramis <ceb@zurich.ibm.com>

* fix(docx): handle unmapped characters in OMML % formatting

Signed-off-by: Cesar Berrospi Ramis <ceb@zurich.ibm.com>

---------

Signed-off-by: Cesar Berrospi Ramis <ceb@zurich.ibm.com>