Remove hermesV1Enabled Gradle property and simplify Hermes version resolution

Since legacy Hermes is no longer supported, remove the hermesV1Enabled
toggle from the Gradle plugin, version.properties, and all build scripts.
HERMES_V1_VERSION_NAME is renamed to HERMES_VERSION_NAME as the single
Hermes version. CMake flags like HERMESVM_HEAP_HV_MODE are now
unconditional.

Author: cipolleschi

private/react-native-fantom/build.gradle.kts

@@ -198,9 +198,7 @@ val configureFantomTester by
               "-DREACT_THIRD_PARTY_NDK_DIR=$reactAndroidBuildDir/third-party-ndk",
               "-DRN_ENABLE_DEBUG_STRING_CONVERTIBLE=ON",
           )
-
       cmdArgs.add("-DHERMES_V1_ENABLED=1")
-
       commandLine(cmdArgs)
       standardOutputFile.set(project.file("$buildDir/reports/configure-fantom_tester.log"))
       errorOutputFile.set(project.file("$buildDir/reports/configure-fantom_tester.error.log"))