[Feature]: Theme Footer Support link or html or component

[iqolome]

What problem does this feature solve?

• ICP Filing is supported
• Friendship link jump
• DIY Footer component

What does the proposed API look like?

Footer 对象

{
 type: 'html' | 'render','string',
data: obj, // Determine by type Determines the final output object
}

[sanyuan0704]

Good advice! And the api would be designed to be more specific.