r/html_reports: Use autodie and replace bareword handles

Signed-off-by: Niels Thykier <niels@thykier.net>
r/harness: Remove bareword file handle

Signed-off-by: Niels Thykier <niels@thykier.net>
private/*: Use autodie and replace bareword file handles

Signed-off-by: Niels Thykier <niels@thykier.net>
coll: use autodie and replace barewords file handles

Signed-off-by: Niels Thykier <niels@thykier.net>