fix(gatsby): added looksLikeADate to check date on schema creation

[wardpeet]

Description

Moment.js is slow at parsing dates so this PR does a lot of extra validation before we fallback to moment. I copied some code from moment.js to parse the ISO formats and do a quick regex myself.

Build Schema on www now is 2s on my machine instead of 60s before.

Checks that are being done:

1. is it a number?
2. does the length of the value comply with any of our formats
3. does the str starts with 4 digites (YYYY)
4. does the str ends with something that looks like a date
5. Small regex to see if it matches any of the defined ISO formats
6. check momentjs

Related Issues

#12692

[wardpeet]

ok so I couldn't get the isDate checks to work how it should. Momentjs does checks for validation of dates like 30 february will never be true but 29 might be. So i added an extra function that checks if it looks like a date which is not bullet proof but probably good enough for schema creation.

[freiksenet]

Thank you Ward!