Replace the version mode Mainline in 6.x (Part II)

[HHobeck]

Description

Create TrunkBasedVersionStrategy implementation and replace the version mode Mainline in 6.x.

Motivation and Context

For more detail please see the following ADR:

• Replace the version mode Mainline in 6.x #3601

Next steps are:

• Create TrunkBasedVersionStrategy implementation (done)
• Create integration tests for TrunkBasedVersionStrategy (I skip this because of the limit time of reviewer)
• Remove Mainline mode <<-- Part of this PR
• Replace VersioningMode with DeploymentMode (pending)
• Add new property with name strategy (type VersioningStrategies) to the configuration root level (pending)
• Create documentation for TrunkBased workflow and add breaking changes notes (pending)

How Has This Been Tested?

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[arturcic]

@HHobeck is it ready for review?

[HHobeck]

@HHobeck is it ready for review?

Yes it is. Thank you for taking the time.

[arturcic]

@HHobeck will you also update the docs according to the changes you made in this PR? Or maybe you add an additional step to update the docs to reflect the changes that you make?

[HHobeck]

I would say to finalize the feature and document it at the end. If you not mind

[arturcic]

Then add to the Description of the Next Steps so we do not forget

[arturcic]

I'd say it looks good to me, there is a small adjustment there, I would also want @asbjornu to have a look

[asbjornu]

Is support for multiple trunks something you think can be added back before v6 goes final?

[HHobeck]

I'm not sure if I find the time because I see this feature as not so important. But anyway I think we should create a feature ticket for this.

[asbjornu]

Looking good!

[arturcic]

Hey @asbjornu if all the changes look good to you please merge the PR, and @HHobeck can move to the next step

[mergify]

Thank you @HHobeck for your contribution!