Add flavor-specific package entry points for browser, node, lite, and react-native variations

[opti-jnguyen]

QoL Enhancement for JS SDK imports for environments that require hard-coding the specific Optimizely JS SDK dist variation.

Uses Node.js package entry points to define flavor-specific entry files to use. Would require flavor-specific definititions for browser, node, lite, and react-native variations to point to within the package.json file that map to the corresponding builds for each.

In response to user ask regarding avoiding verbose imports such as @optimizely/optimizely-sdk/lib/index.node.

[Tamara-Barum]

Internal Ticket Created: FSSDK-9570