[RN 0.88] Add modern exports field to package.json

[leotm]

Sub-issue of

• React Native 0.88 Strict TS API Incompatibility #741

the strict TS API breaks packages that point their package.json legacy "react-native" cond to TS sources

https://github.com/AppAndFlow/react-native-safe-area-context/blob/ae0e83f67bae458e22ce128fd05be01ab1021a03/package.json#L7

which tells tsgo/tsc (via tsconfig, moduleResolution: bundler) to resolve imports to type-check .tsx source files

hitting the errors from deep RN internal imports (error log in parent issue)

the easiest fix is modern package.json exports, without touching the source files

{
  "exports": {
    ".": {
      "types": "./lib/typescript/src/index.d.ts",
      "import": "./lib/module/index.js",
      "require": "./lib/commonjs/index.js"
    },
    "./jest/mock": {
      "types": "./lib/typescript/jest/mock.d.ts",
      "import": "./src/jest/mock.tsx",
      "require": "./src/jest/mock.tsx"
    },
    "./package.json": "./package.json"
  }
}

while preserving the harmless legacy "react-native" condition to keep older bundlers/toolchains working

example patch

diff --git a/package.json b/package.json
index 59b8a5d..79da3e3 100644
--- a/package.json
+++ b/package.json
@@ -147,5 +147,18 @@
     "type": "all",
     "jsSrcsDir": "./src/specs"
   },
-  "packageManager": "yarn@1.22.22"
+  "packageManager": "yarn@1.22.22",
+  "exports": {
+    ".": {
+      "types": "./lib/typescript/src/index.d.ts",
+      "import": "./lib/module/index.js",
+      "require": "./lib/commonjs/index.js"
+    },
+    "./jest/mock": {
+      "types": "./lib/typescript/jest/mock.d.ts",
+      "import": "./src/jest/mock.tsx",
+      "require": "./src/jest/mock.tsx"
+    },
+    "./package.json": "./package.json"
+  }
 }

[leotm]

u thinking @janicduplessis new major ver for this too? noting exports compat with RN 0.79+