This commit adds a new `LoadDockerAuthConfigs` function, which loads all
registry auths that are configured on the host and sends them with the build
command to the docker daemon.
This is needed in case act builds a docker action and the images referenced in
that docker action are located on private registries or otherwise require
authentication (e.g. to get a higher rate limit).
The code is adapted from how the docker cli works:
https://github.com/docker/cli/blob/257ff41304bf121bdf1acdf00a1c7a896ed038d1/cli/command/image/build.go#L323-L332
Co-authored-by: Markus Wolf <[email protected]>
Co-authored-by: Markus Wolf <[email protected]>