[JENKINS-55348] Fix branch view and documentation

[quilicicf]

Goal of this PR (Original Issue)

Fix small mistakes with previous PR on naming strategies:

• The branch and tag views were uglified by the previous PR on some SCM sources because they fill the name and display name with the same value. The current implementation of the code displays something like this in the branch view for these cases: master: master
• The separator that was chosen : may not be the best option because it's already rather heavily used in the display names. Ex: on GitHub, it's frequent to use a commit message as the PR's title to benefit from squash & merge feature. Popular commit message templates tend to use colons which makes things hard to read. I switched to using - in this PR as it's done in the screenshot in the original issue because it looks better.
• A user pointed out in the original issue's comments that the documentation for the display naming strategy didn't match the drop-down list's phrasing. I've fixed it, and added more documentation to help people link the behaviors with the enum values (for people using Job DSL)

Screenshot of the issue

[MathisGuillet1]

👍

[KalleOlaviNiemitalo]

The branch and tag views were uglified by the previous PR on some SCM sources because they fill the name and display name with the same value.

Why would you add the "Job display name strategy" property to a branch source that does so?

… do you mean those SCM sources set the same string as name and display name for branches and tags, but two different strings for pull requests?

[quilicicf]

… do you mean those SCM sources set the same string as name and display name for branches and tags, but two different strings for pull requests?

Exactly 🤷

[jglick]

@jtnord this is amending #374 IIUC?

[quilicicf]

Thanks guys 🙇