Introduce analogue clock time icon

[tecosaur]

With the SVG library (bundled as part of Emacs), we can generate an analogue clock for the current time to-the-minute, instead of using the nearest-hour nerdicon.

I've personally been running this variant of the time segment since https://github.com/seagle0128/doom-modeline/issues/577#issuecomment-1267020963, and so am pretty confident this works as we'd hope.

The one thing I wonder about is whether we can make the svg library be required only when doom-modeline--generate-clock is first called?

Sample screenshot:

[tecosaur]

Following a suggestion from @elken, the svg requirement is now soft and baked into the doom-modeline--generate-clock call.

[seagle0128]

Thank you!