Add chess symbols (and related)

[Enivex]

There's an ungodly number of these symbols, so I'd be surprised if I got everything right.

I mostly followed @MDLC01, though:

• I used only black/white and black/red instead of having stroked/filled as aliases, since these carry an actual meaning here.
• I opted to call the inverted pieces .inv instead of .b. I believe they are more common than the other rotated variants.
• I used the names amazon, empress and princess for the fairy pieces
• I also added the shogi pieces (koma)

There's also 4 symbols for draughts, but they don't seem like they fit under chess.

[T0mstone]

IIUC, "koma" just means "piece", so I'm not sure whether it's descriptive enough.

[Enivex]

IIUC, "koma" just means "piece", so I'm not sure whether it's descriptive enough.

It means piece in Japanese, and it's in a submodule. I don't think there's much opportunity for confusion.

[Enivex]

I just realized that the black pawn also needs a text variation selector, since it can also be an emoji.

[Enivex]

Closing until the multi-character symbols situation is resolved.

[T0mstone]

Reopening since the multi-character symbols situation has been resolved a while ago.

[T0mstone]

The changelog needs to be updated now too (cf. #121 (review)).

[MDLC01]

Note that Unicode also defines symbols used in chess notation, at least ten of which in Miscellaneous Symbols and Arrows, as of Unicode 17.0.0.

[MDLC01]

Additionally, Unicode 17.0.0 assigned four new codepoints under Chess Symbols (see the delta chart).