Improve parseability of type and constant string representations

[paulsc96]

Overview

Enable TypePrinter and various toString()s to produce more parseable output by optionally emitting well-formed SystemVerilog expressions in more situations.

All changes below except 3. keep existing stringifications unchanged by default. All existing code remains compatible through optional fields and parameters.

These changes do not guarantee type or constant parseability, but cover some simple-to-fix gaps in Slang's already quite parseable stringifications.

Changes

TypePrinter

1. Add the skipScopedTypeNames option to TypePrinter to omit suffixed type names from container types.
2. Add the fullEnumTypeoption to TypePrinter to include enum base types.

ConstantValue and SVInt

3. Use assignment patterns ('{...} ) instead of simple brackets ([...]) for container constants.
4. Expose abbreviateThresholdBits to the end user of ConstantValue.toString() and callees to control or suppress integer vector abbreviation as needed.
5. Add the optional exactUnknowns parameter to ConstantValue.toString() and callees to ensure a reversible representation of integer vectors with unknown bits.

[MikePopoloski]

Thanks for the diff. I have a few minor comments but happy to land this once you address them.

[MikePopoloski]

Also as you can probably tell from the failed tests, there are a bunch of eval tests that need to be updated for your ConstantValue toString change to use '{} but I think it's fine to not make that an option and just update the tests instead.

[codecov]

Codecov Report

Merging #649 (52d6532) into master (768c295) will decrease coverage by 0.03%.
The diff coverage is 69.44%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #649      +/-   ##
==========================================
- Coverage   91.23%   91.19%   -0.04%     
==========================================
  Files         185      185              
  Lines       42042    42200     +158     
==========================================
+ Hits        38357    38486     +129     
- Misses       3685     3714      +29     

Impacted Files	Coverage Δ
include/slang/numeric/ConstantValue.h	100.00% <ø> (ø)
include/slang/numeric/SVInt.h	98.50% <ø> (ø)
source/ast/types/TypePrinter.cpp	67.76% <64.28%> (-0.15%)	⬇️
source/numeric/SVInt.cpp	98.79% <71.42%> (ø)
source/numeric/ConstantValue.cpp	72.97% <73.33%> (+0.06%)	⬆️
source/ast/symbols/ParameterSymbols.cpp	80.83% <0.00%> (-4.03%)	⬇️
include/slang/ast/SemanticFacts.h	50.00% <0.00%> (-3.85%)	⬇️
source/ast/ASTSerializer.cpp	63.81% <0.00%> (-2.14%)	⬇️
source/ast/symbols/ClassSymbols.cpp	94.00% <0.00%> (-0.19%)	⬇️
include/slang/ast/Symbol.h	100.00% <0.00%> (ø)
... and 12 more

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[paulsc96]

I chose to make 3. optional now and keep the existing default behavior, maintaining full compatibility.