handling `construction:highway`

[mkoniecz]

What steps will reproduce the problem?

1. Create way with construction:highway=tertiary
2. Create way with highway=construction construction=tertiary
3. Run validator

What is the expected result?

Either it is rendered like highway=construction construction=tertiary or validator offers to fix it to highway=tertiary (or validator offers to add highway=tertiary). Or highway=tertiary is migrated to construction:highway=tertiary

What happens instead?

Please provide any additional information below. Attach a screenshot if possible.

​https://taginfo.openstreetmap.org/keys/construction%3Ahighway#overview

Note that iD developers plan to start considering highway=construction as deprecated and start using construction:highway.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2019-04-03 00:33:43 +0200 (Wed, 03 Apr 2019)
Build-Date:2019-04-03 01:30:50
Revision:14954
Relative:URL: ^/trunk

Identification: JOSM/1.5 (14954 en) Linux Ubuntu 16.04.6 LTS
Memory Usage: 435 MB / 869 MB (277 MB allocated, but free)
Java version: 1.8.0_201-b09, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: :0.0 1920x1080
Maximum Screen Size: 1920x1080
Dataset consistency test: No problems found

Plugins:
+ OpeningHoursEditor (34867)
+ buildings_tools (34904)
+ continuosDownload (82)
+ imagery_offset_db (34867)
+ measurement (34867)
+ reverter (34961)
+ todo (30306)

Validator rules:
+ ${HOME}/Documents/install_moje/OSM software/josm/data/validator/deprecated.mapcss
+ ${HOME}/Documents/install_moje/OSM software/josm/data/validator/unnecessary.mapcss
+ ${HOME}/Documents/install_moje/OSM software/josm/data/validator/combinations.mapcss

Last errors/warnings:
- W: No configuration settings found.  Using hardcoded default values for all pools.
- W: Failed to add ${HOME}/Documents/install_moje/OSM software/josm/data/validator/unnecessary.mapcss to tag checker
- W: java.lang.IllegalArgumentException: Expecting n/node/w/way/r/relation/area, but got '"node'