chore(sdk): drop dsh-plugin-fetch (giget/pacote) — #2 will use native npm/pnpm deps

External-plugin creation will add a package-manager-native dependency
(github:owner/repo#ref or pkg@version) plus a cordis mount instead of fetching
tarballs into a temp dir, so the giget/pacote fetch package is no longer needed.

tsconfig.json

@@ -110,7 +110,6 @@
     { "path": "./packages/sdk/helper" },
     { "path": "./packages/sdk/scripts" },
     { "path": "./packages/sdk/create-sdk" },
-    { "path": "./packages/sdk/plugin-fetch" },
     { "path": "./packages/sdk/telemetry" }
   ]
 }