chore(poc): Use our interactive colour for the border of Inputs

[VincentSmedinga]

Describe the pull request

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What

This shows how our inputs would appear if we made their borders blue like inputs, buttons and form controls.

Why

To evaluate whether we want to go through with this.

How

• Use the default interactive colour for the borders of Date Input, File Input, Password Input, Search Field, Select, Text Area, Text Input, and Time Input.
• Make the borders a pixel thicker in the process – we rarely use 1px, and rightly so: it looks too feeble in combination with our large text sizes.

Checklist

Before submitting your pull request, please ensure you have done the following. Check each checkmark if you have done so or if it wasn't necessary:

• Add or update unit tests
• Add or update documentation
• Add or update stories
• Add or update exports in index.* files
• Start the PR title with a Conventional Commit prefix, as explained here.

Additional notes

• Do it!