Remove legacy JVM-specific file system, shell, and related implementations; migrate to platform-agnostic and common main modules.

src/commonMain/kotlin/mtmc/os/shell/builtins/LoadCommand.kt

@@ -0,0 +1,46 @@
+package mtmc.os.shell.builtins
+
+import mtmc.emulator.MonTanaMiniComputer
+import mtmc.os.exec.Executable.Companion.load
+import mtmc.os.fs.FileSystem
+import mtmc.os.fs.Path
+import mtmc.os.shell.ShellCommand
+import mtmc.tokenizer.MTMCTokenizer
+
+class LoadCommand : ShellCommand() {
+  @Throws(Exception::class)
+  override fun exec(tokens: MTMCTokenizer, computer: MonTanaMiniComputer) {
+    val fs = computer.fileSystem
+    val program = tokens.collapseTokensAsString()
+    require(!(program == null || program.isBlank())) { "missing or required argument 'src'" }
+    val srcPath: Path = getDiskPath(program, fs)
+
+    val exec = load(srcPath)
+    computer.load(exec!!.code, exec.data, exec.graphics, exec.debugInfo)
+    val source = tokens.source
+
+    // set up an argument if given
+    if (tokens.more()) {
+      val firstArgToken = tokens.consume()
+      val startChar: Int = firstArgToken.start
+      val arg = source.substring(startChar)
+      val strippedArg = arg.trim()
+      if (!strippedArg.isEmpty()) {
+        computer.setArg(strippedArg)
+      }
+    }
+  }
+
+  override val help: String
+    get() = """
+                load <exec>
+                    - exec : path to an executable file
+                    """.trimIndent()
+
+  companion object {
+    fun getDiskPath(pathString: String, fs: FileSystem): Path {
+      val path = Path.of("disk" + fs.resolve(pathString))
+      return path.toAbsolutePath()
+    }
+  }
+}