Introduce Arm64 support

[silvin-lubecki]

- What I did
Introduce Arm64 support for docker-app.

- How I did it

• Cross build docker-app plugin to linux-amd64 platform
• Cross build cnab-app-base image to linux-arm64 platform
• Create a manifest list and push it to the hub using docker manifest commands

- How to verify it

• Push a test tag and check on Hub if the image is multi-arch.

- Description for the changelog

• Add Arm64 support for docker-app plugin
• docker/cnab-app-base is now a multi-arch image with linux/arm64 platform

- A picture of a cute animal (not mandatory)

[codecov]

Codecov Report

Merging #777 into master will decrease coverage by 0.08%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #777      +/-   ##
==========================================
- Coverage    70.4%   70.32%   -0.09%     
==========================================
  Files          67       67              
  Lines        3740     3740              
==========================================
- Hits         2633     2630       -3     
- Misses        760      762       +2     
- Partials      347      348       +1

Impacted Files	Coverage Δ
types/parameters/parameters.go	92.06% <0%> (-4.77%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 012748d...743f7fc. Read the comment docs.

[silvin-lubecki]

@doanac I'd love your review here 😄

[doanac]

Thanks! I hate to be too demanding, but would this be a good time to also do armhf as well? We actually use both aarch64 and armhf in our products.

[doanac]

thanks so much!

[silvin-lubecki]

thanks so much!

You're welcome 😸 Well, it still needs to pass the CI, but it's just a matter of time.
@doanac can I ask you to check this PR on your side?

[ulyssessouza]

LGTM