FIO-8954 previously selected option is displayed in metadata with data source = url

[KatrinKhilko]

Link to Jira Ticket

https://formio.atlassian.net/browse/FIO-8954

Description

Made "Allow only available values” available for Select component. Made adjustments for validateValueAvailability method to make sure list of available values to compare is correct for data source = url.

Breaking Changes / Backwards Compatibility

n/a

Dependencies

n/a

How has this PR been tested?

tested manually

Checklist:

• I have completed the above PR template
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• My changes include tests that prove my fix is effective (or that my feature works as intended)
• New and existing unit/integration tests pass locally with my changes
• Any dependent changes have corresponding PRs that are listed above