feat: add checks

[BryanH01]

On taxonomy:

• number of root entries
• list of root entries
• list of the 50 entries with the greatest number of direct children and their number of children

On an entry:

• list of translations present on children but not on the entry
• shortest and longest path to a root : path en length
• number of descendants
• list of properties that are defined on a parent
• list of properties that are already defined on a parent and redefined on the entry
• list of children than redefine one of the property of this entry
• number of children that use a synonym instead of a main id to link to this parent

For a language,
create a “languages” node:

• % of translated entries with at least 3 languages
• list of entries that miss translation (<3)

storing results in sub-node for each language:

• % of translated entries

[alexgarel]

@BryanH01 there has been a misunderstanding here (sorry for that).

I didn't want you to add the checks at parsing time, nor statically.

What should be done is a checks.py file that has all those functions (and maybe one that run all checks and report).

The idea is that after modifications of the taxonomy, @aadarsh-ram code would call those checks to eventually report errors to the user: either on a "warning / error pages" or on single entries (depending on the check).

[alexgarel]

@teolemon this PR is stalled and it does not do the checks the way we want them (we a live API), we keep it just for the neo4j request that can be re-used.

cc: @aadarsh-ram