[Tagging] Mixed paid, free and forbidden parking

[OSMDoudou]

Not totally sure, but I was thinking of:
- the tag opening_hours would cover the period of time when free and paying parking is allowed, so that the forbidden period is the rest of the time
- in addition, the fee tag would cover only the period of time when a fee is due [1]
- add boundary=low_emission_zone to restrict access in case of pollution [2]

[1] https://wiki.openstreetmap.org/wiki/Tag:amenity%3Dparking
[2] https://wiki.openstreetmap.org/wiki/Tag:boundary%3Dlow_emission_zone