Isolate personal data in external file and add boilerplate feature

[maxpowis]

As discussed in #19, consider isolating personal data from resume to a yaml/json aligned with some industry standard.
https://jsonresume.org/schema/ seems to be a good option, considering the wide availability of templates already.
Example of latex boilerplate with a yaml implemented here: https://github.com/maxpowx/invoice-boilerplate/ using https://pandoc.org/MANUAL.html#extension-yaml_metadata_block

[maxpowis]

Decided to not do that as I want to keep control on detailed formatting specs within my cv (e.g.: footnotes, etc.) and am not ready to support all specificities on a complete metadata basis.