support expressions in `@for` macro #555

Job	Run time
build	5m 7s
Julia 1.6 - ubuntu-latest - x64	10m 4s
Julia 1.6 - macOS-latest - x64	6m 58s
Julia 1.6 - windows-latest - x64	17m 27s
Julia 1.7 - ubuntu-latest - x64	3m 52s
Julia 1.7 - macOS-latest - x64	5m 5s
Julia 1.7 - windows-latest - x64	10m 24s
Julia nightly - ubuntu-latest - x64	13m 36s
Julia nightly - macOS-latest - x64	9m 0s
Julia nightly - windows-latest - x64	8m 14s
	1h 29m 47s

Provide feedback