fix: refactor rollup bundling

[Mohammad-Dwairi]

Summary

Refactored Rollup configuration to generate "moduled" entries for each client in the SDK. This enables users to import clients and types from a scoped subpackges.

Import from supply module

import { SupplyClient } from '@expediagroup/lodging-connectivity-sdk/supply';

Import from sandbox module

import { SandboxClient } from '@expediagroup/lodging-connectivity-sdk/sandbox';

Import from payment module

import { PaymentClient } from '@expediagroup/lodging-connectivity-sdk/payment';

In addition, users still able to import from the root package, but modules are aliased due to types conflicts. Importing from the root package is done as the following:

import { SupplyAPI, SandboxAPI, PaymentAPI } from '@expediagroup/lodging-connectivity-sdk';

Additional Improvements

1. Optimized the bundle for Rollup's treeshaking
2. Marked some dependencies as external in rollup config, these will be automatically installed with the SDK by npm instead pf bundling them with the package.
3. Marked the root project and the examples module as private: true to prevent unintended publish.
4. Added entries mappings in the code module pacakge.json to enable host apps resolve the types and main entries.