feat: static credentials provider

[dkoshkin]

Initial implementation, adding the scaffolding and simple functionality where it just reads a file and returns it to stdout.

Tested the plugin with:

$ echo '{"kind":"CredentialProviderResponse","apiVersion":"credentialprovider.kubelet.k8s.io/v1alpha1","cacheKeyType":"Registry","cacheDuration":"10m0s","auth":{"*.registry.io":{"username":"user","password":"password"}}}' > /tmp/image-credentials.json
$ echo '{"kind":"CredentialProviderRequest","apiVersion":"credentialprovider.kubelet.k8s.io/v1alpha1","image":"test.registry.io/foobar"}' | ./dist/static-credential-provider_$(go env GOOS)_$(go env GOARCH)_v1/static-credential-provider /tmp/image-credentials.json
{"kind":"CredentialProviderResponse","apiVersion":"credentialprovider.kubelet.k8s.io/v1alpha1","cacheKeyType":"Registry","cacheDuration":"10m0s","auth":{"*.registry.io":{"username":"user","password":"password"}}}

And the installer:

$ docker run -e CREDENTIAL_PROVIDER_TARGET_DIR=/tmp -v $(pwd)/tmp:/tmp mesosphere/kubelet-image-credential-provider-installer:v0.1.0-dev
time="2022-11-10T01:32:37Z" level=info msg="Installed /tmp/acr-credential-provider"
time="2022-11-10T01:32:37Z" level=info msg="Installed /tmp/ecr-credential-provider"
time="2022-11-10T01:32:38Z" level=info msg="Installed /tmp/static-credential-provider"
time="2022-11-10T01:32:38Z" level=info msg="Wrote credential provider binaries to /tmp\n"