Remove numeric suffix of IR node names if possible

To ensure uniqueness of names numeric suffices are added to IR names like. For example, setting an IR node name to "foo_bar" might result in the IR node actually being named "foo_bar__42" if there already exist other nodes with the name root "foo_bar", This can result many node names with numeric suffixes.

Sometimes, after CSE or DCE there remains only one such name with a given root (e..g, "foo_bar") but still have a numeric suffix (e.g, "foo_bar__42"). In these cases the suffix could be removed. This could be implmented as a pass which sweeps names and removes numeric suffixes where possible.

The motivation is cleaner names in the emitted verilog which more closely correspond to the original source.