fix: allow reserved word 'mod' in exports (#21537)

This problem occurred trying to load tensorflow.js
```
> import * as tf from 'npm:@tensorflow/tfjs';
Uncaught SyntaxError: Identifier 'mod' has already been declared at file:///Users/ry/Library/Caches/deno/npm/registry.npmjs.org/@tensorflow/tfjs/4.14.0/dist/tf.node.js:167:14
    at async <anonymous>:1:33
```

cli/tests/testdata/npm/registry/@denotest/reserved-word-exports/1.0.0/index.cjs

@@ -38,6 +38,7 @@ exports["int"] = "int";
 exports["interface"] = "interface";
 exports["let"] = "let";
 exports["long"] = "long";
+exports["mod"] = "mod";
 exports["native"] = "native";
 exports["new"] = "new";
 exports["null"] = "null";

cli/tests/testdata/npm/reserved_word_exports/main.out

@@ -56,6 +56,7 @@ Download http://localhost:4545/npm/registry/@denotest/reserved-word-exports/1.0.
     interface: "interface",
     let: "let",
     long: "long",
+    mod: "mod",
     native: "native",
     new: "new",
     null: "null",
@@ -109,6 +110,7 @@ Download http://localhost:4545/npm/registry/@denotest/reserved-word-exports/1.0.
   interface: "interface",
   let: "let",
   long: "long",
+  mod: "mod",
   native: "native",
   new: "new",
   null: "null",

ext/node/analyze.rs

@@ -351,6 +351,7 @@ static RESERVED_WORDS: Lazy<HashSet<&str>> = Lazy::new(|| {
     "interface",
     "let",
     "long",
+    "mod",
     "native",
     "new",
     "null",