Support SM2 two-party threshold signature #12

Job	Run time
basic_clang	4m 6s
basic_gcc	4m 10s
check_update	1m 17s
check-ansi	1m 57s
minimal	2m 12s
no-deprecated	3m 56s
address_ub_sanitizer	11m 8s
buildtest	6m 51s
enable_non-default_options	3m 35s
fips_and_ktls	4m 17s
legacy	3m 40s
memory_sanitizer	26m 16s
no-legacy	4m 15s
non-caching	4m 11s
ntls_address_ub_sanitizer	9m 39s
ntls_memory_sanitizer	17m 42s
no-shared (ubuntu-latest)	3m 18s
phe_test	35m 46s
no-shared (macos-latest)	4m 13s
symbol_prefix-test	7m 17s
threads_sanitizer	3m 28s
EC_POINTs_api_test	18m 34s
external-test-pyca (1.51.0, 3.9)	1m 24s
ntls-with-fips	7m 46s
ntls-without-sm234	6m 33s
out-of-source-and-install (ubuntu-latest)	4m 21s
out-of-source-and-install (macos-latest)	7m 9s
sm2-threshold-test	45m 2s
smtc_and_ntls	13m 58s
zkp-build-test	3m 14s
	4h 31m 15s

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