Enable FQCNs for import_playbook to have subdirs

[cavcrosby]

Related to #4362.

[cavcrosby]

Regarding the code analysis failing, ansible uses a similar regex that does not place a limit on the number of subdirectories a user can specify. Currently, I think that's the only applicable workaround to the catastrophic backtracking vulnerability, but even then, I don't think the linter should differ from what ansible sets.

[ssbarnea]

RE_IS_FQCN_OR_NAME = re.compile(r"^\w+((\.\w+){2,})*$")

To quote SonarQube: Make sure the regex used here, which is vulnerable to exponential runtime due to backtracking, cannot lead to denial of service.