feat: sample-gen multipart and form media-type

[mathis-m]

application/x-www-form-urlencoded || multipart/ initial value should rely on sample gen in case it will harvest schema information.

Description

Part of lager refactor issue #6470

Changes:

• Example from sample gen instead of only default and example in case of example | default | 1 enum value

Motivation and Context

Fixes #6621 because the initial value was manually retrieved from the spec. With switching to sample gen fn the case stated in the issue is already implemented. (?url=https://gist.githubusercontent.com/mathis-m/388f6772747dfeb8a0092eac69cfd008/raw/711e6f787da10f1ae57873749f6826f9b3c6be60/Pqo45ggmbT.txt)

How Has This Been Tested?

not - but I don't think we need any test for this because we now use existing logic.

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.

[tim-lai]

@mathis-m PR merged! Thanks for the contribution!