Add recipe for libignition-launch3

[traversaro]

Related to #13551 . This adds the Ignition Launch library.

Support for macOS and Windows is currently blocked by the following issues in dependent libraries:

• Fix macOS build libignition-sensors-feedstock#3
• Enable compilation of part that depend on sdformat and dartsim on Windows libignition-physics-feedstock#12

So for the time being only Linux is enabled, support for the other platforms will be added as soon as the dependencies are ready.

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[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipes/libignition-launch3) and found it was in an excellent condition.

[traversaro]

@wolfv and @Tobias-Fischer already agreed to be maintainers of the ignition libraries in #13551 and related PRs.

[wolfv]

Looks great! Happy to merge whenever you say it's ready :)

[traversaro]

It is ready!

[wolfv]

I had one comment about adding -j${CPU_COUNT} but somehow it doesn't go through on mobile

[traversaro]

I had one comment about adding -j${CPU_COUNT} but somehow it doesn't go through on mobile

You are right, I forgot to add it to the boilerplate that I propagate across repos. I will add it in the feedstock.

[wolfv]

Yeah it's not a big deal but when building locally it's a nice speed up