[Feature Request] Add "axiom" as theorem type

[Zegeri]

Some mathematical texts might use axioms and it would be nice if it were supported by quarto. I suggest using "axm" as tag prefix. For example:

::: {#axm-pairing}
## Pairing

If $x$ and $y$ are sets, then there exists a set which contains $x$ and $y$ as elements. 
:::

[adityam]

On a similar vein, it will be nice to have an asm prefix for "Assumptions".

[mcanouil]

At some point, instead of asking for possibly an infinity of things on that aspect, maybe a feature request allowing user to add custom prefix such as for custom call-outs would be better in the long run.

Note that the feature request is tracked in #3979 and a comment for "assumption" is already there.

[allenmanning]

Thanks for posting and requesting these features @Zegeri and @adityam.

[allenmanning]

Moved to #3979