Having to list all packages isn't very manageable and requires constant
maintenance that is easy to miss. For example, test/e2e/framework/daemonset was
created without adding an entry for it. Promptly one file doesn't use the
intended e2edaemonset alias.
A simpler solution is to support matching the import path against a regular
expression and deriving the intended alias by expanding placeholders (${name},
$1, etc.) with the corresponding submatches from the import path. Example:
k8s.io/kubernetes/test/e2e/framework/([^/]*) -> e2e$1
This support is backwards compatible because normal import paths don't contain
characters that are special in a regular expression and normal aliases don't
contain placeholders.
A regular expression must match the entire import path, otherwise it is
skipped.
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