Add more blackboard bold characters to TeX input method

This patch adds all capital blackboard bold letters and those for "1"
and "2". Most characters are in common use in mathematics, but it does
not seem useful to exclude the few not widely used.

Reference: https://en.wikipedia.org/wiki/Blackboard_bold

* lisp/leim/quail/latin-ltx.el (latin-ltx--define-rules): Add all
the blackboard bold commands from AMSTeX.  (Bug#21103)

lisp/leim/quail/latin-ltx.el

@@ -656,10 +656,34 @@ system, including many technical ones.  Examples:
  ("\\wp" ?℘)
  ("\\wr" ?≀)
 
- ("\\Bbb{N}" ?ℕ)			; AMS commands for blackboard bold
- ("\\Bbb{P}" ?ℙ)			; Also sometimes \mathbb.
+ ("\\Bbb{A}" ?𝔸)			; AMS commands for blackboard bold
+ ("\\Bbb{B}" ?𝔹)			; Also sometimes \mathbb.
+ ("\\Bbb{C}" ?ℂ)
+ ("\\Bbb{D}" ?𝔻)
+ ("\\Bbb{E}" ?𝔼)
+ ("\\Bbb{F}" ?𝔽)
+ ("\\Bbb{G}" ?𝔾)
+ ("\\Bbb{H}" ?ℍ)
+ ("\\Bbb{I}" ?𝕀)
+ ("\\Bbb{J}" ?𝕁)
+ ("\\Bbb{K}" ?𝕂)
+ ("\\Bbb{L}" ?𝕃)
+ ("\\Bbb{M}" ?𝕄)
+ ("\\Bbb{N}" ?ℕ)
+ ("\\Bbb{O}" ?𝕆)
+ ("\\Bbb{P}" ?ℙ)
+ ("\\Bbb{Q}" ?ℚ)
  ("\\Bbb{R}" ?ℝ)
+ ("\\Bbb{S}" ?𝕊)
+ ("\\Bbb{T}" ?𝕋)
+ ("\\Bbb{U}" ?𝕌)
+ ("\\Bbb{V}" ?𝕍)
+ ("\\Bbb{W}" ?𝕎)
+ ("\\Bbb{X}" ?𝕏)
+ ("\\Bbb{Y}" ?𝕐)
  ("\\Bbb{Z}" ?ℤ)
+ ("\\Bbb{1}" ?𝟙)
+ ("\\Bbb{2}" ?𝟚)
  ("--" ?–)
  ("---" ?—)
  ;; We used to use ~ for NBSP but that's inconvenient and may even look like