build(cli): add riscv64 support

[mengzhuo]

Motivation

As riscv growing popularity and being adopted by more projects
https://github.com/carlosedp/riscv-bringup

and commercial Cloud provider like Scaleway https://www.scaleway.com/en/news/scaleway-launches-its-risc-v-servers-in-the-cloud-a-world-first-and-a-firm-commitment-to-technological-independence/

It's possible to run argo workflow by riscv users.

Modifications

Adds riscv64 support

Verification

make dist/argo-linux-riscv64 && ./dist/argo-linux-riscv64

argo prints help verbose.

[Joibel]

This will only support the CLI on riscV, but that's the only component we support on non amd64/arm64 for other less popular architectures.
It will not allow the workflow's kubernetes components to run on riscV.
Anyway, LGTM

[Joibel]

@mengzhuo, you will need to sign your commits according to https://github.com/argoproj/argoproj/blob/main/community/CONTRIBUTING.md. You will need to rewrite this commit to make the DCO check pass.

[agilgur5]

This will only support the CLI on riscV, but that's the only component we support on non amd64/arm64 for other less popular architectures.

^This, see also #12067 for the rest

[agilgur5]

LGTM. There is existing precedent for CLI binaries, as Alan noted