Add brine p

[plgbrts]

This PR continues PR #410 (add brine support)

This PR adds on top of P#410 the creation of WSALT entries in the HISTORY_SCHEDULE.inc

The flownet-testcases/ norne_salt (PR #50 of flownet-testcases repo) is used as testcase

Contributor checklist

• [ x] : This PR closes #381.
• [ x] I have broken down my PR into the following tasks:
  • [x] The creation of WSALT entries in the HISTORY_SCHEDULE.in
• [ x] : I have added tests, or extended existing tests, to cover any new features or bugs fixed in this PR.
  • flownet-testcases/ norne_salt
• [ ] I have considered adding a new entry in CHANGELOG.md.
• [ ] I have considered updating the documentation.

[plgbrts]

You should add an item to the CHANGELOG stating that FlowNet now supports brine simulation.

Other that that it looks nice!

I commented all the places where a potential cumulative vector for salt could be added. I don't know enough about brine simulations to know if it is ever used by someone, but I see the vectors are available in OPM Flow, at least. If it is something that is not used at all we should not add them.

I followed your suggestions to generalise and to allow also for WSPT, WSIT, WSIR, similarly as done e.g. for water production/injection (WWXX).

[plgbrts]

Many thanks for all the good suggestions. I removed the WSIR from WCONHIST.