tree-wide: relax TPM available checks for many cases

In many cases it's essential to know if the firmware supports a TPM, but
in others we should accept it if the firmware doesn't have TPM support,
in particular if we want to run the OS with a software TPM.

Hence, add tpm2_is_mostly_supported() as function similar to
tpm2_is_fully_supported(), with the only difference that the former
doesn't insist on a firmware supported TPM. Then, change a number of
users over to this (but not all).

src/tpm2-setup/tpm2-setup.c

@@ -516,7 +516,7 @@ static int run(int argc, char *argv[]) {
         if (r <= 0)
                 return r;
 
-        if (arg_graceful && !tpm2_is_fully_supported()) {
+        if (arg_graceful && !tpm2_is_mostly_supported()) {
                 log_notice("No complete TPM2 support detected, exiting gracefully.");
                 return EXIT_SUCCESS;
         }