feat(font): fonts customization.

[neoFelhz]

Contributing rules

• Fork the repo and create your branch from canary. Then be sure to put the canary branch as the target for your pull request.
• Please be sure to follow the contributing guidelines, especially for commit message
• Remove the Contributing rules part from this description
• Fill out the other parts from this description

If you don't do so, we might change your pull request's title and using squash to merge your changed.

What kind of change does this PR introduce? (check one with "x")

• Bug fix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

Does this PR introduce a breaking change? (check one with "x")

• Yes
• No

---

Description

Load the font from cdn.

• When using google, theme will load Roboto & Material Icon from fonts.googleapi.com, while Font-Awesome will load from MaterialCDN or local.
• When using baomitu, all the fonts will load from cdn.baomitu.com.

All of them are SSL supported. And cdn.baomitu.com is with HTTP/2 enabled while font.googleapi.com is with h2+quic 37 enabled.

I change the font-family settings variable as well, which may cause BREAKING CHANGES.

---

Verification steps

No verification steps.