Move object method bodies into a separate class when original class is too large

[Nadeeshan96]

Purpose

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$title
Fixes #41279

Approach

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Samples

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Remarks

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Check List

• Read the Contributing Guide
• Updated Change Log
• Checked Tooling Support (#)
• Added necessary tests
  • Unit Tests
  • Spec Conformance Tests
  • Integration Tests
  • Ballerina By Example Tests
• Increased Test Coverage
• Added necessary documentation
  • API documentation
  • Module documentation in Module.md files
  • Ballerina By Examples

[codecov]

Codecov Report

Patch coverage: 92.94% and no project coverage change.

Comparison is base (cf7b31a) 76.33% compared to head (47b217b) 76.34%.
Report is 1 commits behind head on master.

❗ Current head 47b217b differs from pull request most recent head 8f2d66f. Consider uploading reports for the commit 8f2d66f to get more accurate results

Additional details and impacted files

@@            Coverage Diff            @@
##             master   #41398   +/-   ##
=========================================
  Coverage     76.33%   76.34%           
- Complexity    52484    52495   +11     
=========================================
  Files          2881     2881           
  Lines        198455   198519   +64     
  Branches      25799    25809   +10     
=========================================
+ Hits         151498   151554   +56     
- Misses        38598    38601    +3     
- Partials       8359     8364    +5     

Files Changed	Coverage Δ
...llerinalang/compiler/bir/codegen/JvmConstants.java	100.00% <ø> (ø)
...lerinalang/compiler/bir/codegen/JvmPackageGen.java	89.16% <ø> (ø)
...inalang/compiler/bir/codegen/JvmTerminatorGen.java	85.05% <ø> (ø)
...ompiler/bir/codegen/interop/ExternalMethodGen.java	34.44% <ø> (ø)
...lang/compiler/bir/codegen/methodgen/MethodGen.java	95.89% <90.00%> (-0.44%)	⬇️
...allerinalang/compiler/bir/codegen/JvmValueGen.java	93.21% <95.00%> (+0.10%)	⬆️
.../ballerina/runtime/internal/values/ErrorValue.java	84.09% <100.00%> (ø)
...erinalang/compiler/bir/codegen/JvmCodeGenUtil.java	93.33% <100.00%> (+0.03%)	⬆️
...nalang/compiler/bir/codegen/JvmInstructionGen.java	90.39% <100.00%> (ø)

... and 5 files with indirect coverage changes

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[Nadeeshan96]

Closing this PR since we will merge the PR sent from ballerina-platform/ballerina-lang branch: #41409.