Move ci_icon.vue to its own directory

What does this MR do and why?

ci_icon.vue is used widely by components in CI, by moving it to its own directory we can document it with storybook stories moving forward.

Related MRs

• Move ci_icon.vue to its own directory (!139227 - merged) ☝ you are here!
• Add two simple stories for ci_icon (!139239 - merged)
• Draft: Use default icon size in CI status icons (!139243 - closed)

Screenshots or screen recordings

NA

How to set up and validate locally

As long as the build works correctly and jest and rspec pass this change does not need additional validation.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #434472 (closed)