feat: Add configurable permissions for Workers (#8215)

This commit adds new option to "Worker" Web API that allows to 
configure permissions.

New "Worker.deno.permissions" option can be used to define limited
permissions to the worker thread by either:
- inherit set of parent thread permissions
- use limited subset of parent thread permissions
- revoke all permissions (full sandbox)

In order to achieve this functionality "CliModuleLoader"
was modified to accept "initial permissions", which are used
for top module loading (ie. uses parent thread permission set
to load top level module of a worker).

cli/module_loader.rs

@@ -22,6 +22,10 @@ pub struct CliModuleLoader {
   /// import map file will be resolved and set.
   pub import_map: Option<ImportMap>,
   pub lib: TypeLib,
+  /// The initial set of permissions used to resolve the imports in the worker.
+  /// They are decoupled from the worker permissions since read access errors
+  /// must be raised based on the parent thread permissions
+  pub initial_permissions: Rc<RefCell<Option<Permissions>>>,
   pub program_state: Arc<ProgramState>,
 }
 
@@ -38,11 +42,15 @@ impl CliModuleLoader {
     Rc::new(CliModuleLoader {
       import_map,
       lib,
+      initial_permissions: Rc::new(RefCell::new(None)),
       program_state,
     })
   }
 
-  pub fn new_for_worker(program_state: Arc<ProgramState>) -> Rc<Self> {
+  pub fn new_for_worker(
+    program_state: Arc<ProgramState>,
+    permissions: Permissions,
+  ) -> Rc<Self> {
     let lib = if program_state.flags.unstable {
       TypeLib::UnstableDenoWorker
     } else {
@@ -52,6 +60,7 @@ impl CliModuleLoader {
     Rc::new(CliModuleLoader {
       import_map: None,
       lib,
+      initial_permissions: Rc::new(RefCell::new(Some(permissions))),
       program_state,
     })
   }
@@ -118,7 +127,16 @@ impl ModuleLoader for CliModuleLoader {
     let state = op_state.borrow();
 
     // The permissions that should be applied to any dynamically imported module
-    let dynamic_permissions = state.borrow::<Permissions>().clone();
+    let dynamic_permissions =
+      // If there are initial permissions assigned to the loader take them 
+      // and use only once for top level module load.
+      // Otherwise use permissions assigned to the current worker.
+      if let Some(permissions) = self.initial_permissions.borrow_mut().take() {
+        permissions
+      } else {
+        state.borrow::<Permissions>().clone()
+      };
+
     let lib = self.lib.clone();
     drop(state);