Add systematic PRE/POST Tcl hooks for flow steps#3961

Dhirenderchoudhary wants to merge 2 commits intoThe-OpenROAD-Project:masterThe-OpenROAD-Project/OpenROAD-flow-scripts:masterfrom

Dhirenderchoudhary:fix/pre-post-step-hooksDhirenderchoudhary/OpenROAD-flow-scripts:fix/pre-post-step-hooksCopy head branch name to clipboard