[Step Extension] Fix parsing of xml step extension

[poorna2152]

Purpose

Update parsing of xml step extension to match the spec.
https://ballerina.io/spec/lang/master/#xml-step-extend

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

Attention: Patch coverage is 66.51584% with 74 lines in your changes are missing coverage. Please review.

❗ No coverage uploaded for pull request base (xml_step_extension@ee7799b). Click here to learn what that means.

Files	Patch %	Lines
...piler/syntax/tree/XMLStepMethodCallExtendNode.java	25.00%	18 Missing ⚠️
...o/ballerina/compiler/syntax/tree/TreeModifier.java	0.00%	14 Missing ⚠️
.../compiler/internal/parser/tree/STTreeModifier.java	0.00%	8 Missing ⚠️
...ternal/parser/tree/STXMLStepIndexedExtendNode.java	58.82%	7 Missing ⚠️
...nal/parser/tree/STXMLStepMethodCallExtendNode.java	56.25%	7 Missing ⚠️
...io/ballerina/compiler/syntax/tree/NodeFactory.java	64.70%	6 Missing ⚠️
...a/compiler/internal/parser/tree/STNodeVisitor.java	0.00%	4 Missing ⚠️
...inalang/formatter/core/FormattingTreeModifier.java	76.47%	4 Missing ⚠️
...mpiler/internal/parser/tree/STNodeTransformer.java	0.00%	2 Missing ⚠️
...allerina/compiler/syntax/tree/NodeTransformer.java	0.00%	2 Missing ⚠️
... and 2 more

Additional details and impacted files

@@                  Coverage Diff                  @@
##             xml_step_extension   #42722   +/-   ##
=====================================================
  Coverage                      ?   77.13%           
  Complexity                    ?    51242           
=====================================================
  Files                         ?     2928           
  Lines                         ?   204207           
  Branches                      ?    26628           
=====================================================
  Hits                          ?   157518           
  Misses                        ?    38176           
  Partials                      ?     8513           

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