Add first .clang-tidy file #2134

Job	Run time
build-test (ubuntu-20.04, gcc)	1m 9s
test-fuzz	1m 6s
test-coverage	1m 20s
scanbuild	1m 10s
build-test (ubuntu-20.04, clang)	1m 19s
build-test (fedora-32, gcc)	1m 5s
test-mbedtls (ubuntu-20.04)	2m 51s
test-no-crypto-build	1m 21s
build-test (fedora-32, clang)	1m 5s
test-mbedtls (ubuntu-22.04-mbedtls-3.1)	2m 48s
test-tcti-config	1m 20s
build-test (opensuse-leap, gcc)	1m 20s
build-test (opensuse-leap, clang)	1m 22s
coverity-test	0s
build-test (ubuntu-22.04, gcc)	1m 21s
build-test (ubuntu-22.04, clang)	1m 21s
build-test (alpine-3.15, gcc)	1m 21s
build-test (alpine-3.15, clang)	1m 21s
	24m 40s

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