feat: deno doc --html

[bartlomieju]

This commit adds static documentation site generate to "deno doc"
subcommand.

Example:

$ deno doc --html --name="My library" ./mod.ts
# outputs to ./docs/

$ deno doc --html --name="My library" --output=./documentation/ ./mod.ts ./file2.js
# outputs to ./documentation/

$ deno doc --html --name="My library" ./**/mod.ts
# generate docs for all files with "mod.ts" name

Closes #8233

[bartlomieju]

Blocked by #21018

[bartlomieju]

Suggestions welcome for other prompts

[dsherret]

LGTM

[dsherret]

Should this be log::info!?

[bartlomieju]

Using log::info! seems to not print this info by default. I'm gonna revert it meh, it was print to stderr