refactor: default to RSA PKCS#1 instead of RSA-PSS in signature recommendations

[tshakalekholoane]

Is your feature request related to a problem? Please describe.

While the RSA-PSS is arguably a better alternative to RSA PKCS#1 v1.5, it might be better to recommend the latter instead given that the latter has better adoption.

Some protocols such as SSH also only specify RSA PKCS#1 v1.5 and so a recommendation to use the RSA-PSS instead would be wrong in this case.

But one also has to be careful since some standards i.e., the BSI, have deprecated the use of RSA PKCS#1 v1.5 (see p. 12 of BSI-TR-02102-2) so special care should be taken to ensure that this is reflected in the logic as well.