feat: support _meta.pre_function to execute custom logic before execution of each phase #981

Job	Run time
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/http3/admin)	14m 35s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/plugin/[a-k]*)	14m 35s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/plugin/[l-z]*)	14m 36s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/admin t/cli t/config-center-yaml...	14m 36s
build (ubuntu-20.04, linux_openresty, lua-resty-worker-events, t/node t/pubsub t/router t/script ...	14m 34s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/http3/admin)	14m 14s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/plugin/[a-k]*)	14m 36s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/plugin/[l-z]*)	14m 34s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/admin t/cli t/config-center-yaml t/cont...	14m 36s
build (ubuntu-20.04, linux_openresty, lua-resty-events, t/node t/pubsub t/router t/script t/secre...	14m 37s
	2h 25m 33s

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