Support floats, binary & octal literals (with underscores)

[LemmusLemmus]

Added

• Highlighting for numbers with exponential, e.g. 3E4 or 4e-1.
• Highlighting for the numbers infinity and NaN.
• Octal and binary constants, e.g. 0b01 and 0o37.
• Numbers with possibly absurd but valid usages of underscores. All of these are valid numbers in Nushell:

  +___3.____
  ____NAN____
  _____.__4__
  ___-___Inf
  ___0__x___3___44___44____
  _+_____3___e___0___
  _00_0_._3___e___00__03__

  In other words, underscores can go anywhere in numeric literals. I have however not supported valid numbers such as _-_inf____in_ity, since that would make the regex much less readable than it already is, and I think that anyone who uses that kind of constant does not deserve pretty syntax highlighting for it >:(.

Notes

• I have used possessive quantifiers everywhere as to avoid potential catastrophic backtracking.

[fdncred]

I would only want to support what is valid nushell syntax. Are all of these valid nushell syntax for floats, binary, and octals?

[LemmusLemmus]

Surprisingly, yes they are all valid. I suppose Nushell is pretty lax with regards to where underscores are allowed, which is reasonable considering that there are different conventions for how to group digits (but I think Nushell is maybe a bit too lax).

[fdncred]

oh wow, i didn't know we supported 3e4 and nan. lol. it's hard keeping up sometimes. thanks!