Add issue and PR templates. #212

Job	Run time
build-native-gcc	2m 49s
build-native-llvm	3m 21s
test-native-gcc	8m 8s
build-aarch64-gcc	3m 23s
test-native-llvm	7m 29s
build-aarch64-llvm	3m 55s
build-armhf-gcc	2m 5s
build-armhf-llvm	1m 29s
build-ppc64el-gcc	2m 59s
build-ppc64el-llvm	2m 28s
build-s390x-gcc	2m 5s
build-s390x-llvm	2m 13s
build-riscv64-llvm	2m 26s
test-${{ matrix.arch }}-${{ matrix.compiler }} (qemu_cpu: "${{ matrix.qemu_cpu }}")	0s
	44m 50s

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