New measure: Bicycle infrastructure

[mpadge]

Use dodgr::dodgr_dists_categorical() calculation with edges in 3 categories of:

1. Perfect for bicycles (green, parks, separated bicycle ways);
2. Okay for bicycles (bicycle lanes alongside traffic); or
3. Unsuited (in vehicular traffic without bicycle lanes).

Weight those respectively 1, 0.5, and 0, add the categorical weights along all ways from each point out to distances of 5 and 10 km, and convert to proportional distances. Average over all to get metric of local bicycle infrastructure. That will then simply need to be converted to metric of "bicycle unsuitability", as 1 - metric, so that lower values are good like all other UTA stats.

[mpadge]

tag	weight
highway=cycleway	1
cycleway=track/lane/opposite_lane	1
cycleway:left=track/lane/opposite_lane	1
cycleway:right=track/lane/opposite_lane	1
bicycle=use_sidepath	1
bicycle=designated	1
cycleway=share_busway	0.5
highway=living_street/residential/path	0.5
cycleway=shared/shoulder	0

[mpadge]

dodgr::weight_streetnet() has now been updated to return all bicycle-relevant columns, ready to use to address this issue.

[mpadge]

Re-opening to include this statistic in the output of uta_export()