[AAE-12065] Add isDefault flag to dropdown

[DiogoABastos]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (check one with "x")

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation
• Other... Please describe:

What is the current behaviour? (You can also link to an open issue here)
If dropdown field had the same id as the DEFAULT_OPTION.id, it would be taken as the default option

https://alfresco.atlassian.net/browse/AAE-12065
https://github.com/Alfresco/alfresco-apps/pull/5894

What is the new behaviour?
Add isDefault flag to allow users to use the DEFAULT_OPTION.id as an id, without making such an option the default option
Is compatible with JSON forms previously created

Does this PR introduce a breaking change? (check one with "x")

• Yes
• No

If this PR contains a breaking change, please describe the impact and migration path for existing applications: ...

Other information:

[eromano]

what happens if isDefault is not present in the JSON because is a form previously created?

[DiogoABastos]

what happens if isDefault is not present in the JSON because is a form previously created?

isDefault flag is defaulted to false. The problem is that when the dropdown has the default option enabled, it will be regarded as a normal option because of the isDefault's default value. I'll make some changes to account for that

[eromano]

can we add a unit that cover this scenario?

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[DiogoABastos]

No need for this changes anymore. https://alfresco.atlassian.net/browse/AAE-12065?focusedCommentId=1192290