Replace global intrinsic functions with consistent extension-based system.
Each bridged type now defines standardized lift/lower operations:

Swift side (type extensions):
- bridgeJSLowerParameter/Return: Swift -> Wasm core types
- bridgeJSLiftParameter/Return: Wasm core types -> Swift

JavaScript side (JSGlueGen):
- Corresponding lift/lower functions for JS <-> Wasm interop

Adds CodeFragmentPrinter for improved code organization.
Reduces generated code complexity across both Swift and JS.

Clean up variable declaration in VariableDeclSyntax visitor.

Introduce _BridgedSwiftTypeLoweredIntoSingleWasmCoreType protocol
to formalize lift/lower operations. All basic types (Bool, Int,
Float, Double) now conform to this protocol with standardized
bridgeJS* methods.

Add _BridgedSwiftHeapObject and _BridgedSwiftEnumNoPayload protocols
for heap objects and enums respectively.

Update generated code and test snapshots to use new protocol-based
intrinsic functions.

…gedClass

Add _JSBridgedClass protocol with lift/lower operations for JavaScript
objects imported into Swift. Update ImportTS code generation to use
new protocol-based bridgeJS* methods.

Update all generated ImportTS Swift files and test snapshots to use
the new bridgeJS* method calls instead of legacy functions.

This is a workaround for the issue that reference to imported bjs
wasm functions can't be eliminated in debug builds, even if they
are not reachable at runtime without explicit BridgeJS usage.

Remove unused _BridgedSwiftTypeLoweredIntoWasmCoreType protocol
and fix incomplete documentation comment for the remaining protocol.