Refactor pgp_key_search_t #3386

Job	Run time
ubuntu-latest [CC gcc; botan; shared libs on; GnuPG stable]	4m 21s
cmake-offline-googletest-src	4m 16s
ubuntu-latest [CC clang; botan; shared libs on; GnuPG stable]	4m 11s
system-sexpp, sexpp shared libs on, rnp shared libs on	3m 8s
cmake-offline-googletest	4m 58s
system-sexpp, sexpp shared libs on, rnp shared libs off	2m 48s
ubuntu-latest [CC gcc; openssl; shared libs on; GnuPG stable]	4m 24s
package-source	31s
system-sexpp, sexpp shared libs off, rnp shared libs on	2m 57s
ubuntu-latest [CC clang; openssl; shared libs on; GnuPG stable]	4m 48s
system-sexpp, sexpp shared libs off, rnp shared libs off	2m 59s
ubuntu-20.04 [CC gcc; openssl; shared libs on; GnuPG stable]	4m 22s
ubuntu-latest [CC gcc; botan; shared libs off; GnuPG stable]	4m 39s
package	1m 39s
debian-tests	13s
	50m 14s

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