refactor(paxos): extract leader election notification (#1514) #897

Job	Run time
pre_job	6s
linux (x86_64-unknown-linux-gnu)	3m 37s
linux (i686-unknown-linux-gnu)	4m 34s
linux-cross (aarch64-unknown-linux-gnu, aarch64)	3m 36s
macos-universal (universal2-apple-darwin)	3m 55s
linux-cross (armv7-unknown-linux-gnueabihf, armv7)	3m 40s
windows (x86_64-pc-windows-msvc, x64)	11m 21s
windows (i686-pc-windows-msvc, x86)	10m 26s
windows (aarch64-pc-windows-msvc, x64)	12m 51s
Release	0s
	54m 6s

Provide feedback