[FIRRTL] more strict connect semantic

[sequencer]

I observe that, the current firrtl.connect only checks the src width not larger than the dst width, but not vice versa. since in the firrtl parser logic we already define some the padding and truncate logic, we can make firrtl.connect be more strict, e.g. checking width exactly same to find width bug in the early phase.

[darthscsi]

strictconnect has those semantics. connect is essentially dead through the pipeline and exists for parsing and fixing up the padding and truncation early on.