KImg: Add 'appearanceOverrides'

[MisRob]

Summary

KImg accepts the Vue dynamic styles object, for example

{
   width: '100%',
   textDecoration: 'none',
   color: $themeTokens.text
}

via appearanceOverrides prop, which will override the component's styling

Epic

• KImg Component #368

Acceptance criteria

• Using appearanceOverrides modifies the appearance of the component
• Its attributes always take precedence over any specified styling (e.g. internal component's styles, styles calculated from props, ...)
• Documentation is updated with all new features. Contains guidance and examples whenever relevant.

Linked issues

• Blocked by

  • KImg: Implement the basic component #369
  • KImg: Add scaling and placeholder logic #370

• Blocking

  • KImg: Polish documentation #374

[EshaanAgg]

Hi! I want to work on this issue.
Since the Kolibri team is on a break for the holidays, I am taking the liberty to work on the issue without being explicitly assigned. Hope that's okay!