Add the possibility to explicitly tag sidewalks as allowed for bicycles

[wielandb]

Most of the code for this was already implemented but as of the discussion in streetcomplete#2276 and subsequent discussions it was removed in StreetComplete because if bicycles are allowed on the sidewalk may need expert knowledge depending on the legislation, and it may not be surveyable on-the-ground easily. Since requireing expert knowledge is no problem in SCEE, I have (re)implemented the functionality here.

• Cycleway quest and overlay
  • The StreetSideSelect Form now offers an option to tag "None, but cycling allowed on sidewalk" which will tag sidewalk:[side]:bicycle=yes
  • Answering "none" will now also remove sidewalk:[side]:bicycle=yes
  • Compatibility to SC is still given. SC will see this answer as "none" and answering none will not change the sidewalk tagging in case it's there.
  • The colour in the overlay for SIDEWALK_EXPLICIT has been changed to be a continious cyan line, so that SIDEWALK_OK can have the dashed cyan line
• Seperate Cycleway Form
  • It's now possible to tag a seperate way as explicitly allowed for bicycles or explicitly disalowed for bicycles
  • Answering PATH or NOT_DESIGNATED will now also remove bicycle=, since choosing it now means that the user intents there to be no statement about bicycles

[westnordost]

I am okay with re-adding it though, given that it is explicitly tagged as being signed that way, i.e. adding bicycle:signed=yes (sidewalk:<side>:bicycle:signed=yes respectively) too in that case and making it clear to the user that this option should only be chosen when there is a sign about that.

streetcomplete#4913

If this was implemented upstream instead of SCEE, a lot more users will profit of this.

[wielandb]

Nice to hear! I will open a PR upstream. 🙂

[westnordost]

I did a quick review of the PR in the current state. Some comments:

• note that when bicycle:signed=yes is added, when choosing a different option, it also has to be removed again
• the cycleway tagging and parsing is very well tested through unit tests. Changes made on it should also lead to tests being added/modified.