Sidecars from template pods

[coderanger]

Right now only the template container is carried over to the migration job. While not all sidecars should be copied, it would be good if the default was to copy all of them as well as allowing some kind of include/exclude list based on container names.

Proposed API:

SidecarInclude *[]string `json:"sidecarInclude,omitempty"`
SidecarExclude *[]string `json:"sidecarExclude,omitempty"`

If neither is specified, all sidecars (i.e. all containers other than the template container) are copied. Include means "only these", exclude is "all but these" (with neither copying the template container since that's already handled). Specifying both should be a validation error.