Switched implementation of P0315Visitor from `std::variant` to compil… #1113

Job	Run time
Linux Clang - Format check	24s
GCC 14 / LLVM 20 @ Ubuntu Code Coverage (libc++) @amd64	5m 19s
GCC 14 / LLVM 20 @ Ubuntu Code Coverage & Debug @arm64	3m 51s
GCC 14 / LLVM 20 @ Ubuntu Release @arm64	1m 20s
GCC 14 / LLVM 20 @ Ubuntu Code Coverage (libc++) @arm64	5m 8s
GCC 14 / LLVM 20 @ Ubuntu Release LLVM source tree	1m 56s
GCC 14 / LLVM 20 @ Ubuntu Code Coverage & Debug @amd64	3m 58s
GCC 14 / LLVM 20 @ Ubuntu Release @amd64	1m 14s
Clang 20 / LLVM 20 @ macOS Debug	48s
Clang 20 / LLVM 20 @ macOS Release	3m 17s
Clang 20 / LLVM 20 @ macOS Coverage & Debug	2m 56s
Final Deploy	0s
	30m 11s

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