Remove restriction on the project's package name

There are restrictions regarding how modules are called, but given that packages are tight to repositories anyway; there's no way someone can publish and use an aiken package on 'aiken-lang' without being part of the organization. So the restriction on the command-line is pointless. Plus, it prevents us from using 'aiken-lang' as a placeholder name for tutorials.

crates/aiken-project/src/package_name.rs

@@ -13,17 +13,6 @@ pub struct PackageName {
 }
 
 impl PackageName {
-    pub fn restrict(&self) -> Result<(), Error> {
-        if self.owner.starts_with("aiken") {
-            return Err(Error::InvalidProjectName {
-                reason: InvalidProjectNameReason::Reserved,
-                name: self.to_string(),
-            });
-        }
-
-        Ok(())
-    }
-
     fn validate(&self) -> Result<(), Error> {
         let r = regex::Regex::new("^[a-z0-9_-]+$").expect("regex could not be compiled");