feat(common): impl division of Int256 and double precision

[shanicky]

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What's changed and what's your intention?

This pull request introduces new arithmetic operations for performing division between int256 and floating point numbers, resulting in a float64 scalar. Changes include the addition of new operations to "general_div" in arithmetic_op.rs and "int256" in types.rs, as well as new tests to verify arithmetic operations with Int256 values. Finally, new conversion routines were added in num256.rs to enable conversions between Int256 and float64 Scalar types.

Checklist For Contributors

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
  - [ ] I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features Sqlsmith: Sql feature generation #7934).
• I have demonstrated that backward compatibility is not broken by breaking changes and created issues to track deprecated features to be removed in the future. (Please refer to the issue)
• All checks passed in ./risedev check (or alias, ./risedev c)

Checklist For Reviewers

• I have requested macro/micro-benchmarks as this PR can affect performance substantially, and the results are shown.

Documentation

• My PR DOES NOT contain user-facing changes.

Click here for Documentation

Types of user-facing changes

Please keep the types that apply to your changes, and remove the others.

• Installation and deployment
• Connector (sources & sinks)
• SQL commands, functions, and operators
• RisingWave cluster configuration changes
• Other (please specify in the release note below)

Release note

[codecov]

Codecov Report

Merging #9169 (6186d83) into main (9bf890a) will decrease coverage by 0.01%.
The diff coverage is 97.05%.

@@            Coverage Diff             @@
##             main    #9169      +/-   ##
==========================================
- Coverage   70.86%   70.85%   -0.01%     
==========================================
  Files        1200     1200              
  Lines      199974   200007      +33     
==========================================
+ Hits       141711   141723      +12     
- Misses      58263    58284      +21     

Flag	Coverage Δ
rust	70.85% <97.05%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/expr/macro/src/types.rs	94.37% <50.00%> (-0.57%)	⬇️
src/common/src/types/num256.rs	64.85% <100.00%> (+1.15%)	⬆️
src/expr/src/vector_op/arithmetic_op.rs	72.14% <100.00%> (+1.34%)	⬆️

... and 9 files with indirect coverage changes

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