fix(future): Emit deno install warning less often, suggest deno install in error message (#24706)

Two small changes:

- In our BYONM errors, suggest running `deno install` instead of `npm
install` if `DENO_FUTURE` is set
- Only emit warning about `deno install` changes if you do `deno install
<foo>` with deno_future unset

cli/npm/byonm.rs

@@ -286,9 +286,14 @@ impl CliNpmResolver for ByonmCliNpmResolver {
       concat!(
         "Could not find \"{}\" in a node_modules folder. ",
         "Deno expects the node_modules/ directory to be up to date. ",
-        "Did you forget to run `npm install`?"
+        "Did you forget to run `{}`?"
       ),
       alias,
+      if *crate::args::DENO_FUTURE {
+        "deno install"
+      } else {
+        "npm install"
+      }
     );
   }