feat(ci): add unified "AWS: Build, Test, Copy to regions and Release" workflow

Single workflow_dispatch chaining the three standalone AWS workflows:
  build-ami            -> build x86_64 + aarch64 AMIs with Packer
  test-ami             -> launch each AMI, assert release/arch/dnf
  copy-ami             -> copy each AMI to all regions, make public, gen wiki data
  prepare-data-for-wiki-> merge both arches, open ONE wiki PR
  release-ami-to-marketplace -> release each AMI to its arch product

Stages are chained on job results: a failing test leg skips copy +
release, so a broken AMI is never copied/made public/released. The wiki PR
is opened by the single prepare-data-for-wiki job (not a per-arch matrix),
which merges the x86_64 + aarch64 data into one MD/CSV and creates exactly
one PR - the two arches never race to create conflicting PRs.

Inputs are ami-build.yml's version_major + notify_mattermost. test_ami,
make_public, draft, release_to_marketplace and public_product are omitted
and act as fixed values (test_ami=true, make_public=true, draft=false,
release_to_marketplace=true, public_product=true), so the standalone
dev-product / draft-PR escape hatches are not exposed here. The standalone
ami-build.yml / ami-copy.yml / ami-to-marketplace.yml are left unchanged.

Author: yuravk