Add lang lib related function support

[pasindufernando1]

Purpose

This PR addresses three aspects related to adding support to lang lib function usage via low code

1. Resolve langlib typeNames to their supertypes — Introduced TypeParameterReplacer to substitute internal lang lib type parameters (e.g. array:Type, stream:ErrorType) with their human-readable supertypes (e.g. (any|error),
   error) throughout the form/property model.
2. Hide result type in inferred type scenarios — When a type was replaced by a supertype placeholder, the result type field is hidden in the UI since showing a generic (any|error) to the user isn't useful.
3. Update getSourceCode to handle lang lib functions — At source generation time, infers the concrete return type by looking up the actual variable's type via the semantic model during lang lib scenarios

Fixes : wso2/product-ballerina-integrator#1750

Now the experience looks like below, where the return type is hidden for lang lib related functions and the actual type is inferred during the saving process

Screen.Recording.2026-02-16.at.10.00.26.mov

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Pull request overview

This pull request adds comprehensive support for Ballerina lang lib function usage in the low-code flow model generator. The implementation addresses three key aspects: (1) type parameter replacement to convert internal lang lib type parameters (e.g., array:Type, stream:ErrorType) into human-readable supertypes (e.g., (any|error), error), (2) automatic hiding of result type fields in the UI when types are replaced by generic placeholders, and (3) enhanced source code generation that infers concrete return types by analyzing actual variable types via the semantic model during lang lib function calls.

Changes:

• Introduced TypeParameterReplacer utility class to systematically replace lang lib internal type parameters with their corresponding supertypes across multiple lang lib modules (array, error, map, stream, xml, table, value)
• Enhanced CallBuilder with resolveLangLibReturnType method that dynamically resolves concrete return types at source generation time by inspecting variable types through the semantic model
• Updated test configurations for lang lib functions to reflect the new type parameter replacements and proper type hiding behavior

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
TypeParameterReplacer.java	New utility class providing systematic type parameter replacement for lang lib modules with mappings for array, error, map, stream, xml, table, and value modules
CallBuilder.java	Added lang lib detection, return type resolution logic, and concrete type inference by analyzing visible symbols through the semantic model
FunctionCall.java	Integrated lang lib return type resolution before falling back to type inference
MethodCall.java	Integrated lang lib return type resolution for method call scenarios
SourceBuilder.java	Added newVariableWithType method to support explicit type specification
Property.java	Integrated type parameter replacement in ballerinaType setter
FormBuilder.java	Applied type parameter replacement to type and returnType properties, with automatic hiding when replacement occurs
ModelGeneratorTest.java	Uncommented updateConfig call (typically kept commented across test suite)
function_call-lang-lib_5.json	New test configuration for array:enumerate function demonstrating type resolution from CSV[] to [int, CSV][]
lang_lib-*.json	Updated test configurations for various lang lib functions (array, error, map, stream, table) with replaced type parameters and hidden result types
function_call/main.bal	New test source file for function call scenarios
function_call-langlib.bal	Additional test source file for lang lib function call scenarios
Ballerina.toml	Test project configuration

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