More granular token types

Motivation
This ties into #2849. There are a few token types that are missing right now and languages usually approximate. I.e. TOML has a date token type and all tokens have a number alias for coloring.

Description
A few new token types, I would like to suggest:

• time (or date or date-time): A type for dates, times, and other time instances.
  We have a few languages that contain literals for dates and times. Right now, most of them use the number type.
• character (or char): A type for character literals.
  Some languages support literals for string and characters (e.g. C/C++, C#, Java, Rust, Scheme). Themes should be able to give these literals a different color.
• ip-address (or ip-addr or ip): A type for IPv4 and IPv6 addresses.
  Some languages support IP address literals.
• attr-assign: A token used to assign an attribute value to an attribute name.
  Some people what to highlight the assignment operator of attributes differently (example).
• doc: An alias for different types to indicate that a string or comment is used for documentation (e.g. JavaDoc comments or Python docstrings). E.g. <span class="token comment doc">/** foo */</span>.

Start by reading the related issue #2849 and the attribute assignment example in components/prism-markup.js. Review how the proposed token types relate to existing aliases and decide which names and semantics are accepted; the work is done when the agreed token types are specified and implemented consistently.