Add `k-which-python` binary in nix #3598

Job	Run time
Version Sync	9s
Nix flake (self-hosted, linux, normal)	5m 19s
Nix flake (macos-13, macos-13)	17m 41s
Nix flake (MacM1, self-macos-12)	25m 20s
Check Java code formatting	25s
K Ubuntu Jammy Package	20m 53s
K Tests	26m 27s
Performace Tests	11m 16s
	1h 47m 30s

Provide feedback