[Tagging] Tag proposal for gender-neutral toilets

[Cadence Ember]

> That may be true in your country but it is not so in the UK.   For most
> public toilets here there is a lock on the disabled facility, needing a
> special key. 

I did not know about that. Is this something that could be tagged with 
`access=`? The toilet is itself gender neutral, it's just that there are 
additional requirements if one wants to use it.