Improve treeshakeability of build artifacts

[aryaemami59]

This PR:

• [X] Brings all of devModeChecks underneath process.env.NODE_ENV checks to ensure they are erased during production builds.
• [X] Adds @__PURE__ annotation to some of the function call sites to improve treeshakeability.
• [X] Adds getUseIsomorphicLayoutEffect with @__PURE__ annotation to improve further treeshakeability.
• [X] Adds @__PURE__ annotations to all react-is symbols.
• [X] Sets browser field in package.json to browser artifact. (Not sure if we want to keep the browser artifact so if not let me know and I can get remove it).