[K2/K1 FP] Fix context-receivers flag passing in full-pipeline test

We should copy `-Xcontext-receivers` flag from the original arguments
during the setup of compiler arguments in the FP test

Otherwise, UNSUPPORTED_CONTEXTUAL_DECLARATION_CALL diagnostic gets
triggered where it shouldn't be present

compiler/fir/modularized-tests/tests/org/jetbrains/kotlin/fir/AbstractFullPipelineModularizedTest.kt

@@ -152,6 +152,7 @@ abstract class AbstractFullPipelineModularizedTest : AbstractModularizedTest() {
             args.pluginClasspaths = originalArguments.pluginClasspaths?.mapNotNull {
                 substituteCompilerPluginPathForKnownPlugins(it)?.absolutePath
             }?.toTypedArray()
+            args.contextReceivers = originalArguments.contextReceivers
 
         } else {
             args.jvmTarget = JVM_TARGET