Add support for arm64

[marcofranssen]

To support deployment to arm64 cluster nodes using the helm-charts in multi architecture clusters it would be great if tornjak also has an arm64 build.

See this PR how I contributed this to spire:

spiffe/spire#3607

Currently I'm working around deployment issues by using a nodeSelector to force Spire back to amd64 nodes for all the tornjak involved components.

nodeSelector:
  kubernetes.io/arch: amd64

[mrsabath]

See this spiffe/spire#3607 and spiffe/spire#1984 as a reference

[maia-iyer]

closed by #358 and #347