Support svg images in the features section in home layout

[MarkusKeck]

Is your feature request related to a problem? Please describe.

Currently only emojis are supported in the features section in home layout, which is already great, but there are a lot of cases where a custom image would be a better fit.

Open discussion
#1589 (comment)

Describe the solution you'd like

 features:
  - icon: [LINK TO SVG IMAGE]
    title: my title
    details: my details
    link: https://github.com/vuejs/vitepress
    linkText: Let's jump right in

Describe alternatives you've considered

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the docs.
• Read the Contributing Guidelines.
• Check that there isn't already an issue that asks for the same feature to avoid creating a duplicate.

[brc-dd]

@userquin might wanna create a PR for this? IIRC you patched it for someone on Discord.