Optionally make java executable path contribute to the daemon id.

This change will allow to start Kotlin daemon instances using different
from the current user JDK version and use it to compile Kotlin files.
Old behaviour, when java executable path is not set, is still working
 and still,by default, using current user JDK version.

For example, user for some reason wants to use JDK 1.8 as active one,
 but compile current project using JDK 16.

Main goal is to support Gradle toolchains.

^KT-45611 In Progress

compiler/daemon/daemon-client/src/org/jetbrains/kotlin/daemon/client/KotlinCompilerClient.kt

@@ -367,8 +367,14 @@ object KotlinCompilerClient {
     }
 
 
-    private fun startDaemon(compilerId: CompilerId, daemonJVMOptions: DaemonJVMOptions, daemonOptions: DaemonOptions, reportingTargets: DaemonReportingTargets): Boolean {
-        val javaExecutable = File(File(CompilerSystemProperties.JAVA_HOME.safeValue, "bin"), "java")
+    private fun startDaemon(
+        compilerId: CompilerId,
+        daemonJVMOptions: DaemonJVMOptions,
+        daemonOptions: DaemonOptions,
+        reportingTargets: DaemonReportingTargets
+    ): Boolean {
+        val daemonJavaExecutable = compilerId.javaExecutable
+            ?: File(File(CompilerSystemProperties.JAVA_HOME.safeValue, "bin"), "java")
         val serverHostname = CompilerSystemProperties.JAVA_RMI_SERVER_HOSTNAME.value ?: error("${CompilerSystemProperties.JAVA_RMI_SERVER_HOSTNAME.property} is not set!")
         val platformSpecificOptions = listOf(
                 // hide daemon window
@@ -380,7 +386,7 @@ object KotlinCompilerClient {
                 listOf("--illegal-access=permit")
             else emptyList()
         val args = listOf(
-                   javaExecutable.absolutePath, "-cp", compilerId.compilerClasspath.joinToString(File.pathSeparator)) +
+                   daemonJavaExecutable.absolutePath, "-cp", compilerId.compilerClasspath.joinToString(File.pathSeparator)) +
                    platformSpecificOptions +
                    daemonJVMOptions.mappers.flatMap { it.toArgs("-") } +
                    javaIllegalAccessWorkaround +