Update insertions styling

[gerteck]

Overview of changes:

• Updated styling of the <cv-insertion> component
• Add attribute options for text alignment, outline styles, etc.
• Updated documentation
• Update some behavior as well (e.g. default content is now styled, with an option to remove border).

Related to #278

SEMVER impact of the PR:

• Major (when you make incompatible API changes)
• Minor (when you add functionality in a backward compatible manner)
• Patch (when you make backward compatible bug fixes)

Checklist: ☑️

• Updated the documentation for feature additions and enhancements
• Added tests for bug fixes or features
• Linked all related issues
• No unrelated changes

Merge Instructions:

• For feature branches merging to develop: Prefer Squash and Merge.
• For release/hotfix branches merging to main, or subsequent sync back-merges merging to develop: ONLY use Create a Merge Commit.