XCSP3 Competition Compatibility

[Dekker1]

This PR aims to provide parsing support for all XCSP3 instances that are formulated according to the XCSP3 competition rules.

The main parts that are missing:

• Meta constraint support (group, block, and slide)
• Matrix / Tuple variants of some constraints.

Some additional details about the expected features is found in huub-solver/huub#179.

[codecov]

Codecov Report

❌ Patch coverage is 18.07760% with 929 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.55%. Comparing base (958f80d) to head (1025579).
⚠️ Report is 21 commits behind head on develop.

Files with missing lines	Patch %	Lines
crates/xcsp3-serde/src/constraint.rs	24.68%	421 Missing and 3 partials ⚠️
crates/xcsp3-serde/src/expression.rs	4.29%	377 Missing and 2 partials ⚠️
crates/xcsp3-serde/src/lib.rs	28.00%	119 Missing and 7 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #253      +/-   ##
===========================================
- Coverage    69.31%   67.55%   -1.77%     
===========================================
  Files          123      123              
  Lines        31827    32890    +1063     
  Branches     31827    32890    +1063     
===========================================
+ Hits         22062    22218     +156     
- Misses        9106    10006     +900     
- Partials       659      666       +7     

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