Refactoring: Add new constant Models.Commit.EmptyTreeSHA1 #2916

Job	Run time
Prepare version string	4s
Build / Build Windows x64	3m 49s
Build / Build macOS (Intel)	2m 55s
Build / Build Windows ARM64	4m 18s
Build / Build Linux	2m 52s
Build / Build Linux (arm64)	2m 58s
Build / Build macOS (Apple Silicon)	1m 54s
Package / Package macOS (osx-arm64)	22s
Package / Package Windows (win-arm64)	26s
Package / Package Linux (linux-arm64)	50s
Package / Package Linux (linux-x64)	55s
Package / Package macOS (osx-x64)	20s
Package / Package Windows (win-x64)	23s
	22m 6s

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