fix: move the fig complete import to an optional require (#1080)

By moving the `@fig/complete-commander` package to an optional require
done at runtime, we can avoid jest trying to import it and causing an
error about ESM packages. This should also generally resolve any errors
even if someone needs to use the completion package, due to the forced
use of the CJS require statement

ref: #1077

.changeset/stale-pillows-talk.md

@@ -0,0 +1,6 @@
+---
+'nest-commander': patch
+---
+
+Move the fig completion package to an optional import to get around jest
+throwing an error about esm packages

packages/nest-commander/src/completion.factory.ts

@@ -1,5 +1,3 @@
-/* eslint-disable @typescript-eslint/ban-ts-comment */
-import { addCompletionSpecCommand } from '@fig/complete-commander';
 import type { INestApplicationContext } from '@nestjs/common';
 import { Command } from 'commander';
 import type { CompletionFactoryOptions } from './completion.factory.interface';
@@ -50,7 +48,15 @@ export class CompletionFactory {
     }
 
     if (parsedOptions.fig) {
-      addCompletionSpecCommand(commander);
+      try {
+        // eslint-disable-next-line @typescript-eslint/no-var-requires
+        const { addCompletionSpecCommand } = require('@fig/complete-commander');
+        addCompletionSpecCommand(commander);
+      } catch {
+        throw new Error(
+          `There was a problem creating the fig completion. Did you make sure to install "@fig/complete-commander"?`,
+        );
+      }
     }
   }