Deprecate python_binary in favor of pex_binary

[Eric-Arellano]

Reasons:

1. Users have expressed interest in other formats than Pex, such as Pyinstaller. We don't want to privilege Pex over those other formats.
2. More explicit to users what it is Pants is doing. python_binary is not some magical thing; it is an interface around the Pex tool.
   • Reminder: we are framing Pants as "an orchestrator around the tools you already use". A theme of 2.0 has been to reduce places where Pants is magical, e.g. our revised __init__.py handling.

We want to make this change before 2.0 is released to the world.

[ci skip-rust]
[ci skip-build-wheels]

[Eric-Arellano]

I originally wanted to add a sed snippet, but gave up. Sed has some differences between macOS and Linux that I personally find hard to navigate.

The snippet is easy with rg and sd (modern Rust alternative), but too few users have those installed.

Distributing a Python script felt super overkill.

--

Lmk if we should in fact add some snippet, or at least the regex ^python_binary\(.

[jsirois]

We use sed -Ee "..." for mac and linux in out own scripts successfully and stably. Did you need some sed feature beyond -E extended regexps?:

$ git grep -w sed *.sh
build-support/bin/contributors.sh:    | sed -e 's/;.*$//'
build-support/bin/contributors.sh:    sed -E -e "s|^|+ |" >> CONTRIBUTORS.md
build-support/bin/release-changelog-helper.sh:        sed -Ee "s|^\(#([0-9]+)\)$|https://github.com/pantsbuild/pants/pull/\1|"
build-support/bin/release-changelog-helper.sh:        sed -Ee "s|^.*(https?://[^ ]+).*$|\1|" | \
build-support/bin/release-changelog-helper.sh:        sed -Ee "s|[/\.]+$||"
build-support/bin/release.sh:    PEX_VERSION="$(requirement pex | sed -e "s|pex==||")"

[cosmicexplorer]

sed -Ee 's#^python_binary\(#pex_binary(#g' would work I think? I wonder if #9434 would become more tolerable now since we already have libcst as a dependency? It would be able to act on BUILD files that aren't perfectly formatted is all (where ^python_binary() may not necessarily catch all of them).

[cosmicexplorer]

A suggestion for after the 2.0 release is I believe how to appropriately consider #9434.

[Eric-Arellano]

Thank you John and Danny for the help!

[jsirois]

As to reasons: there is only one - python_binary has pex specific fields ... so it should be pex specific. This reasoning is generic and can be applied consistently to all our target types.

[coveralls]

Coverage remained the same at 0.0% when pulling 020b30c on Eric-Arellano:pex-binary into f678abf on pantsbuild:master.