feat: Deprecate "import assertions" with a warning (#24743)

This commit deprecates "import assertions" proposal that has been
replaced with "import attributes".

Any time an import assertion is encountered a warning will be printed
to the terminal. This warning will be printed for both local and 
remote files (ie. user code and dependencies).

Import assertions support will be removed in Deno 2.

cli/cache/code_cache.rs

@@ -80,6 +80,10 @@ impl CodeCache {
       data,
     ));
   }
+
+  pub fn remove_code_cache(&self, specifier: &str) {
+    Self::ensure_ok(self.inner.remove_code_cache(specifier))
+  }
 }
 
 impl code_cache::CodeCache for CodeCache {
@@ -158,6 +162,15 @@ impl CodeCacheInner {
     self.conn.execute(sql, params)?;
     Ok(())
   }
+
+  pub fn remove_code_cache(&self, specifier: &str) -> Result<(), AnyError> {
+    let sql = "
+      DELETE FROM codecache
+      WHERE specifier=$1;";
+    let params = params![specifier];
+    self.conn.execute(sql, params)?;
+    Ok(())
+  }
 }
 
 fn serialize_code_cache_type(