Co-authored-by: qcorradi <q.corradi22@imperial.ac.uk>
Co-authored-by: Zachary Snow <zach@zachjs.com>

- Add script to drop parameters from VCDs.
- Bump the version of iverilog used in CI. I couldn't use anything never
  than eab37efb due a pending iverilog issue.
- Standardize around Python 3 in test cases.

- error suite runs in both regular and verbose mode
- add helper for extracting "flags" from test files
- common assertMatch, assertNotMatch helpers
- remove unused assertExists helper
- fix un-escaped wildcard in assert_deferred_nonzero.sv

- use iverilog's -gstrict-expr-width throughout test suite
- add warnings for excess bits or padding zeroes in number literals
- add new --oversized-numbers parameter to retain support for unsized
  numbers wider than 32 bits
- localized use of oversized numbers to new truncate test suite which
  verifies the behavior of both modes, and compares against the known
  behavior of iverilog

Workarounds for resolved iverilog issues have been removed.

- automatic pass-through test suite coverage
- fix codegen for interface based typedefs
- allow declaration of generic interface ports in module body
- fix codegen for comments within for loop initialization
- fix codegen of class param decls

- ensure concats and repeats stay unsigned
- defer unbased-unsized conversion to enable cast semantics
- disable inaccurate folding of binary operations of based numbers
- fix typeof and size cast binop signedness logic
- fix typeof $unsigned and $signed
- test harness allows production of `integer unsigned`

- cast functions in separate scopes are no longer omitted or removed
- package item reordering excludes locally declared names
- test runner ensures output is stable after first iteration

- dimensions flattening conversion only flattens packed dimensions
- conversion for packing arrays when necessary (preserves memories)
- added coverage for array with multiple packed dimensions
- test runner no longer forbids multi-dim accesses after conversion
- Decl and subordinate types derive Ord