`enclosingSource` parameter on visit* methods is always `declaration.source`

[rvandermeulen]

After #123, every visit* definition method takes enclosingSource: KtSourceElement? = null, and every caller in AnalyzerCheckers.kt passes the same value: declaration.source.

val source = declaration.source ?: return
visitor?.visitClassOrObject(declaration, ..., context, enclosingSource = source)
visitor?.visitPrimaryConstructor(declaration, ..., context, enclosingSource = source)
// ... 6 more, all identical

The optional/nullable parameter buys nothing: no caller omits it, no caller passes a different value. And because it's optional, forgetting it silently drops enclosing_range from the output. We hit this in mozsearch/semanticdb-kotlinc#23 when a fork-specific SemanticEnumEntryChecker quietly missed the field.

What if we instead dropped the parameter and derived it inside the visitor from the FirX argument it already accepts?

fun visitClassOrObject(firClass: FirClassLikeDeclaration, element: KtSourceElement, context: CheckerContext) {
    val enclosing = firClass.source ?: element
    cache[firClass.symbol].with(firClass.symbol).emitAll(element, Role.DEFINITION, context, enclosing)
}

Benefits:

• New visit* methods or new checker implementations can't silently miss enclosing_range; the visitor owns the derivation.
• Removes eight redundant enclosingSource = source arguments from AnalyzerCheckers.kt.
• Single source of truth for how enclosing_range maps to each FirX type.

Happy to send a patch if that suggestion works for you!

[linear]

OSS-24212