macros: add stamp for unquoting a template body

[alaviss]

Summary

Add stamp to std/macros , which takes a template body and applies
it immediately. This is the same behaviour as the previous quote
that was changed after #1393.

Details

After #1393 we have a hole in
the stdlib for quote -like interpolation but with automatic binding
of symbols to reduce boilerplate. Various libraries within the ecosystem
such as criterion and npeg have found the feature useful and
extensively employ it.

Reintroduces old quote behavior as stamp , without support for
custom operators and explicitly document the template-like nature of
stamp 's body as well as its pitfalls.

This macro was originally written and shared to Matrix by @zerbina.

[saem]

Minor correction in the doc block to make it explicit what the behaviour of stamp is, also I'll update the PR body a bit, just lead with the introduction of the new macro and its behaviour.

[zerbina]

Thank you for the elaborate documentation and examples! I'm not super happy of having this behaviour be in the standard library, but at least it's properly documented now, with all it's quirks.

There's one problem with the documentation that needs fixing, and some few other things that should be changed, but this looks good to me otherwise.

[saem]

Updated the PR body so it leads with the change.

[zerbina]

/merge

[github-actions]

Merge requested by: @zerbina

Contents after the first section break of the PR description has been removed and preserved below:

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Notes for Reviewers

• Unlike the version shared on Matrix, this version excludes result from being bound automatically.