Simplified runtime command script location querying.

TODO

src/lib-sieve/cmd-discard.c

src/lib-sieve/cmd-keep.c

src/lib-sieve/cmd-redirect.c

src/lib-sieve/ext-fileinto.c

src/lib-sieve/ext-reject.c

src/lib-sieve/plugins/enotify/cmd-notify.c

src/lib-sieve/plugins/enotify/ext-enotify-common.c

src/lib-sieve/plugins/enotify/ext-enotify-common.h

src/lib-sieve/plugins/enotify/tst-notify-method-capability.c

src/lib-sieve/plugins/enotify/tst-valid-notify-method.c

src/lib-sieve/plugins/notify/cmd-notify.c

src/lib-sieve/plugins/vacation/cmd-vacation.c

src/lib-sieve/sieve-actions.c

src/lib-sieve/sieve-actions.h

src/lib-sieve/sieve-interpreter.c

src/lib-sieve/sieve-interpreter.h

src/lib-sieve/sieve-result.c

src/lib-sieve/sieve-result.h

src/sieve-tools/debug/cmd-debug-print.c