Build docker images for linux/amd64 and linux/arm64

[Olsenius]

I have changed the build to build both linux/amd64 and linux/arm64 docker images.
This should solve issue #458.

I tried to reuse the current github secrets where possible. Some more will need to be added. Here are my current working secrets i use on https://github.com/Olsenius/azure-key-vault-to-kubernetes/actions

[Arkessler]

Any way to help move this along? This PR would make akv2k8s viable for our use-case (thank you very much for putting it up Olsenius!)

[tspearconquest]

Try to ping the team on the public slack (linked from the main page of this repo but I'll paste it here also:

Join our Slack Workspace to ask questions to the akv2k8s community.

I have had success in the past by doing that

[larsf96]

@181192
Could you or someone of the team please take a look here? As arm64 usage is growing fast, it would be very nice to have this PR merged

[rfavreau]

Hello, I tested the "spvest/azure-keyvault-controller:1.7.1" image into a aarch64 cpu architecture but i always have the error message exec /usr/local/bin/azure-keyvault-controller: exec format error.
Is it the correct tag that enabled this feature ?

root@RevPi119089:~# lscpu
Architecture:                       aarch64
CPU op-mode(s):                     32-bit, 64-bit
Byte Order:                         Little Endian
CPU(s):                             4
On-line CPU(s) list:                0-3
Thread(s) per core:                 1
Core(s) per socket:                 4
Socket(s):                          1
Vendor ID:                          ARM
Model:                              3
Model name:                         Cortex-A72
Stepping:                           r0p3
CPU max MHz:                        1500.0000
CPU min MHz:                        600.0000
BogoMIPS:                           108.00
L1d cache:                          128 KiB
L1i cache:                          192 KiB
L2 cache:                           1 MiB
Vulnerability Gather data sampling: Not affected
Vulnerability Itlb multihit:        Not affected
Vulnerability L1tf:                 Not affected
Vulnerability Mds:                  Not affected
Vulnerability Meltdown:             Not affected
Vulnerability Mmio stale data:      Not affected
Vulnerability Retbleed:             Not affected
Vulnerability Spec rstack overflow: Not affected
Vulnerability Spec store bypass:    Vulnerable
Vulnerability Spectre v1:           Mitigation; __user pointer sanitization
Vulnerability Spectre v2:           Vulnerable
Vulnerability Srbds:                Not affected
Vulnerability Tsx async abort:      Not affected
Flags:                              fp asimd evtstrm crc32 cpuid

[rfavreau]

Hello, It's resolved with 1.7.3 tag. Thanks a lot for your work.