Adds the unsafe DECIMAL to integer downcasts

[rchowell]

Relevant Issues

The following explicit/unsafe casts were missing in the type definitions.

CAST(<decimal> AS INT2)     -- > int16l|missing
CAST(<decimal> AS INT4)     -- > int32|missing
CAST(<decimal> AS INT8)     -- > int64|missing
CAST(<decimal> AS BIGINT)   -- > int64|missing
CAST(<decimal> AS INT)      -- > int|missing

Description

Adds the unsafe DECIMAL to integer downcasts.

Other Information

• Updated Unreleased Section in CHANGELOG: [YES/NO]
  No

• Any backward-incompatible changes? [YES/NO]
  No

• Any new external dependencies? [YES/NO]
  No

• Do your changes comply with the Contributing Guidelines
  and Code Style Guidelines? [YES/NO]
  Yes

License Information

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[github-actions]

Conformance comparison report

	Base (1e1a71f)	3cd4498	+/-
% Passing	92.54%	92.54%	0.00%
✅ Passing	5384	5384	0
❌ Failing	434	434	0
🔶 Ignored	0	0	0
Total Tests	5818	5818	0

Number passing in both: 5384

Number failing in both: 434

Number passing in Base (1e1a71f) but now fail: 0

Number failing in Base (1e1a71f) but now pass: 0

[codecov-commenter]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (dae1ab3) 72.17% compared to head (06e9da6) 72.15%.
Report is 1 commits behind head on main.

Files	Patch %	Lines
.../org/partiql/lang/syntax/impl/PartiQLPigVisitor.kt	90.24%	1 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1342      +/-   ##
============================================
- Coverage     72.17%   72.15%   -0.02%     
+ Complexity     2097     2095       -2     
============================================
  Files           221      221              
  Lines         15973    15984      +11     
  Branches       2892     2896       +4     
============================================
+ Hits          11528    11534       +6     
- Misses         3639     3641       +2     
- Partials        806      809       +3     

Flag	Coverage Δ
CLI	11.86% <ø> (ø)
EXAMPLES	80.28% <ø> (ø)
LANG	80.78% <90.24%> (-0.03%)	⬇️

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[yliuuuu]

Let's make those explicit as well, for consistent with DECIMAL since right now we are kind of inflating those two types during inferring.

[yliuuuu]

LGTM.