fix(rating): explicit enable rating if required vuln-checks are enabled

[magnuslarsen]

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Fixes #2665 - by explicitly enabling rating if all required vulnerability checks are enabled

do_rating is false by default, but is set to true with set_scanning_defaults() which is run when no parameters are passed (or when --full (maybe a few other options as well) is passed)

When do_rating=true (i.e. when set_scanning_defaults() is called) the set_rating_state() function is never ran.
(see https://github.com/testssl/testssl.sh/blob/3.2/testssl.sh#L24260-L24266)

So... set_rating_state() is only run when do_rating=false; which means we have to set do_rating=true inside the function if all required vuln-checks are enabled.
I did leave the do_rating=false return in there, as it provides valuable readability. Let me know if you want that out there; I can easily inverse the logic :-)

So this fix will leave cases where no arguments are passed (or --full, ...) with no changes; but correctly fix cases where one would pass all required parameters (as in the referenced issue)

[drwetter]

Thanks a bunch @magnuslarsen