Add a boilerplate for the xtask concept

This shall provide a task to build the cmake module.

xtask/src/main.rs

@@ -0,0 +1,24 @@
+use structopt::StructOpt;
+
+#[derive(Debug, StructOpt)]
+pub struct CMakeOptions {}
+
+#[derive(Debug, StructOpt)]
+pub enum Command {
+    #[structopt(name = "cmake")]
+    CMake(CMakeOptions),
+}
+
+#[derive(Debug, StructOpt)]
+#[structopt(name = "xtask")]
+pub struct ApplicationArguments {
+    #[structopt(subcommand)]
+    pub command: Command,
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let opt = ApplicationArguments::from_args();
+
+    println!("Hello, world!");
+    Ok(())
+}