Refactor pgp_key_search_t #3391

Job	Run time
ubuntu-latest [CC gcc; botan; shared libs on; GnuPG stable]	4m 19s
ubuntu-latest [CC clang; botan; shared libs on; GnuPG stable]	4m 7s
ubuntu-latest [CC gcc; openssl; shared libs on; GnuPG stable]	4m 54s
ubuntu-latest [CC clang; openssl; shared libs on; GnuPG stable]	4m 28s
ubuntu-20.04 [CC gcc; openssl; shared libs on; GnuPG stable]	3m 53s
ubuntu-latest [CC gcc; botan; shared libs off; GnuPG stable]	4m 22s
cmake-offline-googletest-src	4m 34s
cmake-offline-googletest	4m 17s
system-sexpp, sexpp shared libs on, rnp shared libs on	2m 50s
system-sexpp, sexpp shared libs on, rnp shared libs off	2m 43s
system-sexpp, sexpp shared libs off, rnp shared libs on	2m 50s
system-sexpp, sexpp shared libs off, rnp shared libs off	2m 49s
package-source	33s
package	1m 17s
debian-tests	11s
	48m 7s

Provide feedback