[Enhancement] Affix functionality for kirby-input

[tspringborg]

Describe the enhancement

Increasingly there's a use for prefix and suffix elements on kirby-input.

Specific usecases:
Adding kr or similar as a suffix
Adding the calculated age in years as a suffix.
Adding a loading indicator as a prefix when something is loading.

Describe the solution you'd like

Preferably add 2 more @input's to the kirby-input directive. Suffix input and prefix input.
The input should take a TemplateRef or a simple string. The simple string would should a default styled text while a TemplateRef would meet all other needs.

Have you considered any alternatives?

I have made a directive for our own project but preferably it should be a part of the kirby-input directive.

Are there any additional context?

---

Checklist:

The following tasks should be carried out in sequence in order to follow the process of contributing correctly.

Refinement

• Request that the issue is tech refined; do not proceed until this is done.

Implementation

The contributor who wants to implement this issue should:

• Make sure you have read: "Before you get coding".
• Signal to others you are working on the issue by assigning yourself.
• Create a branch from the develop branch following our branch naming convention.
• Publish a WIP implementation to Github as a draft PR and ask for feedback.
• Make sure you have implemented tests following the guidelines in: "The good: Test".
• Update the cookbook with examples and showcases.

Review

Once the issue has been implemented and is ready for review:

• Do a self-review.
• Create a pull-request. If you created a draft PR during implementation you can just mark that as "ready for review".

[jkaltoft]

Closing issue. Duplicate of #459