K2. Minor. Rename FirConstExpression to FirLiteralExpression

FirConstExpression is usually confused with "constant" calculations,
while in fact, it just denotes a simple literal expression
and `1 + 1` isn't represented by a FirConstExpression.

^KT-64314 Fixed

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/BuilderConfigurator.kt

@@ -411,7 +411,7 @@ object BuilderConfigurator : AbstractFirBuilderConfigurator<FirTreeBuilder>(FirT
 //            useTypes(whenExpressionType)
 //        }
 
-        noBuilder(constExpression)
+        noBuilder(literalExpression)
 
         builder(samConversionExpression) {
             withCopy()

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/FirTreeBuilder.kt

@@ -95,7 +95,7 @@ object FirTreeBuilder : AbstractFirTreeBuilder() {
     val continueExpression by element(Expression, loopJump)
     val catchClause by element("Catch", Expression)
     val tryExpression by element(Expression, expression, resolvable)
-    val constExpression by element(Expression, expression)
+    val literalExpression by element(Expression, expression)
     val typeProjection by element(TypeRef)
     val starProjection by element(TypeRef, typeProjection)
     val placeholderProjection by element(TypeRef, typeProjection)

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt

@@ -227,7 +227,7 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
             +field("receiver", expression)
         }
 
-        constExpression.configure {
+        literalExpression.configure {
             val t = withArg("T")
             +field("kind", constKindType.withArgs(t), withReplace = true)
             +field("value", t)