multiarch: Build multiarch binaries and images

[Billy99]

Since bpfman-operator is moving to it's own repo, no longer build and push the bpfman-operator and bpfman-agent from the bpfman repo, but instead, build and push from the bpfman-operator repo.

Rework the Makefile such that it no longer loops through each architecture. Building all architectures is done in github actions. The Makefile still allows local cross compiling for a single architecture, just not all architectures in one command. This simplifies the Makefile and yaml files loading images don't need -amd64 appended anywhere.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 27.04%. Comparing base (49345cd) to head (45fc3fa). Report is 3 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #24 +/- ## ========================================== + Coverage 26.36% 27.04% +0.67% ========================================== Files 75 75 Lines 5112 6083 +971 ========================================== + Hits 1348 1645 +297 - Misses 3600 4274 +674 Partials 164 164 ``` | [Flag](https://app.codecov.io/gh/bpfman/bpfman-operator/pull/24/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bpfman) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/bpfman/bpfman-operator/pull/24/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bpfman) | `27.04% <ø> (+0.67%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=bpfman#carryforward-flags-in-the-pull-request-comment) to find out more.

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