Command to look up codepoint from a character

Related problem

Related: #14174 - The seq char command doesn't work well for non-alpha characters.

Rather than fixing seq char, what if we deprecate it (or move a new version to the Standard Library.

The problem at the moment is that (AFAICT) we have no way to get the codepoint for a character in order to know where it lies in the ASCII (or Unicode) table.

Describe the solution you'd like

Either a new command or an extension to the char command to be able to look up the codepoint for a character. For example:

let start = (char --int-from-char 'A')
$start
# => 65
let end = (char --int-from-char 'D')
$end
# => 68

# Replace the `seq char` with:
$start..$end | each {char --integer $in}
# => ╭───┬───╮
# => │ 0 │ A │
# => │ 1 │ B │
# => │ 2 │ C │
# => │ 3 │ D │
# => ╰───┴───╯

Since we don't have a "character" type, the string passed to char --int-from-char should be only one grapheme cluster in length or it should error, I think.

Shouldn't be limited to ASCII, but all Unicode characters should return their codepoint. For example:

char --int-from-char '✔'
# => 10004

Describe alternatives you've considered

No response

Additional context and details

No response

Start by reviewing the existing char command and seq char behavior, then read related issue #14174 for context. Done should mean a command or char extension accepts one grapheme cluster and returns its Unicode codepoint, including non-ASCII characters, with invalid input handled as specified.