bug#53592: 26.3; Bind `M-:' to `pp-eval-expression' and enhance output

[ndame]

You put too many things in the bug IMO. It's a lot. We talked about better eval output,

so this bug should be about that. The output.

Changing the output can be done in parallel to implementing syntax highlight which

the other bug is about. Mixing rebinding M-: here is just confusing things.

Like when you change a system you don't submit a single huge patch which changes

many things at once, because it's harder to see through. You submit multiple smaller

patches which  are easier to digest. Similarly, bugs should have a narrower focus and

when that is done, then there can be a next bug about a some other change, etc.

Just my 2 cents..