Add useDirectusFields() composable

[yoavf]

This pull request introduces a new composable useDirectusFields, including a playground button and relevant documentation.

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

useDirectusFields exposes an important part of directus: collection fields.

• src/runtime/composables/useDirectusFields.ts: Added the useDirectusFields composable with methods getFields, getField, createField, updateField, and deleteField.

Documentation updates:

• docs/content/2.composables/9.useDirectusFields.md: Added documentation for the useDirectusFields composable, including usage examples for each method.

Playground application updates:

• playground/app.vue: Added a new button to fetch fields and integrated the getFields method from useDirectusFields. [1] [2] [3] [4]

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes (if not applicable, please state why) - not applicable because there are no existing tests. I'm happy to add some, but a separate MR should introduce a test framework.

[vercel]

@yoavf is attempting to deploy a commit to the Conner's projects Team on Vercel.

A member of the Team first needs to authorize it.

[Intevel]

Can you add a generic type here to the docs? Like in the playground usage.

[yoavf]

@Intevel done!