Remove ESM wrapper (#312)

Fixes #305... again again.

The `esm` wrapper (as described in
bufbuild/protobuf-es#509) creates problems
when using a peer dependency that defines it's exports without an import
proxy (in our case, react-query).

# Current situation

Our exports look like:

```json
{
  "exports": {
    ".": {
      "node": {
        "import": "./dist/proxy/index.js",
        "require": "./dist/cjs/index.js"
      },
      "module": "./dist/esm/index.js",
      "import": "./dist/proxy/index.js",
      "require": "./dist/cjs/index.js"
    }
  }
}
```

The above meant the following:
- When the **application** imported `QueryClientProvider` from
`@tanstack/react-query`, it resolved to the `esm` version of the context
- When the **library** imported `useQuery` from `@tanstack/react-query`,
it resolved instead to the `cjs` version of the package (since NextJS
SSR is considered a "node" environment)

This mismatch between the esm and cjs versions causes a problem
detecting context

# Alternatives considered

We could expose our own hooks/components with a one-to-one mapping from
`@tanstack/react-query` and require our own `QueryClientProvider` to be
initialized. This would bypass these kinds of issues, but introduce more
setup and potential for confusion. It would mean that using
`react-query` for anything non-connect related would require an
additional query client provider which MAY actually be the same client
depending on where (node/browser) it's running.

# Reason we chose this solution

By not using an `ESM` wrapper, we avoid these possible import
mismatches. It does introduce the possibility of dual package hazard
with class instances (where instanceof is used, like with ConnectError)
but we don't use any of that in connect-query so we can be relatively
safe in that regard.

packages/connect-query/package.json

@@ -10,10 +10,9 @@
   },
   "scripts": {
     "clean": "rm -rf ./dist/*",
-    "build": "npm run build:cjs && npm run build:esm && npm run build:proxy",
+    "build": "npm run build:cjs && npm run build:esm",
     "build:cjs": "tsc --project tsconfig.build.json --module commonjs --outDir ./dist/cjs --declaration --declarationDir ./dist/cjs && echo >./dist/cjs/package.json '{\"type\":\"commonjs\"}'",
     "build:esm": "tsc --project tsconfig.build.json --module ES2015 --verbatimModuleSyntax --outDir ./dist/esm --declaration --declarationDir ./dist/esm",
-    "build:proxy": "node ../../scripts/gen-esm-proxy.mjs .",
     "generate": "buf generate --path eliza.proto",
     "test": "jest",
     "format": "prettier . --write --ignore-path ./.eslintignore && eslint . --fix && license-header",
@@ -24,12 +23,8 @@
   "main": "./dist/cjs/index.js",
   "exports": {
     ".": {
-      "node": {
-        "import": "./dist/proxy/index.js",
-        "require": "./dist/cjs/index.js"
-      },
       "module": "./dist/esm/index.js",
-      "import": "./dist/proxy/index.js",
+      "import": "./dist/esm/index.js",
       "require": "./dist/cjs/index.js"
     }
   },