AddUser: Specific error message for unit users

[MatthiasZepper]

Distinct error message if the user to be added to a project is a unit user.

• Tests passing
• Black formatting
• [ - ] Migrations for any changes to the database schema
• Rebase/merge the dev branch
• Note in the CHANGELOG

[i-oden]

@MatthiasZepper which card is this connected to?

[MatthiasZepper]

@MatthiasZepper which card is this connected to?

None. This afternoon, we both - Sofia and me - were puzzled when she couldn't invite me to the system because I still had a lingering, yet expired, invite for a unit user and the error message rather indicated a typo in the specified user role. It was quicker to fix right away than to generate a card for it first...

[i-oden]

@MatthiasZepper which card is this connected to?

None. This afternoon, we both - Sofia and me - were puzzled when she couldn't invite me to the system because I still had a lingering, yet expired, invite for a unit user and the error message rather indicated a typo in the specified user role. It was quicker to fix right away than to generate a card for it first...

@MatthiasZepper Then Phil has already created a PR for this #1036

[codecov]

Codecov Report

Merging #1039 (84c9d4c) into dev (d57f2c5) will decrease coverage by 0.02%.
The diff coverage is 66.66%.

❗ Current head 84c9d4c differs from pull request most recent head fcc56e5. Consider uploading reports for the commit fcc56e5 to get more accurate results

@@            Coverage Diff             @@
##              dev    #1039      +/-   ##
==========================================
- Coverage   87.58%   87.55%   -0.03%     
==========================================
  Files          27       27              
  Lines        2955     2957       +2     
==========================================
+ Hits         2588     2589       +1     
- Misses        367      368       +1     

Impacted Files	Coverage Δ
dds_web/api/user.py	87.39% <66.66%> (-0.21%)	⬇️

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[i-oden]

Works well 👍🏻