[FR] set fonts for normal text and monospace text separately

### Description

Look, we are almost adopting AppFlowy, and one of the major complaints I hear here is the single-font setting approach. Since I'd like the test to pass and AppFlowy to be available to all of us, I'm personally [treat it as just another, personal user request] writing this feature request, namely:
- allow users to set different fonts for normal text and monospace, just like Obsidian, Typora, etc. allow you.

If you look at ... .. you see that you can only set **one** single font for everything, meaning that *everything* will be Ubuntu Sans for now.

### request
We'd like inline code and code blocks to use another font, say, Ubuntu Sans Mono, or whatever. This ain't possible, see:

The text in the pink rectangle uses another font, whatever it is. It's not even the pretty Ubuntu Sans font defined as the workspace font, which, in my opinion, is a major bug--it should at least be uniform.

Now, the feature that caught me was the comment|note feature [see the green ellipsis in the pic above]. I freaking **love** it.

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Now, as an example of what I mean, look at, say, Typora:

Result: code blocks and inline code use Ubuntu Sans Mono, and normal text uses the Ubuntu Sans font. THAT IS IT.

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This is also the reason we standardised on Gecko-based browsers, because one can both pick separate fonts for normal and monospace text AND, and this is the killer feature, force that setting so that websites always use our predefined font settings, see example on Firefox:

Thanks for considering this.

Cheers.

### Impact

HIGH

### Additional Context

_No response_