fix: Making search facets an object instead of ES6 map

[adilansari]

Describe your changes

• facets in SearchResult being an ES6 map was not getting serialized to string
• changing them to object serializes it to string correctly

- private readonly _facets: ReadonlyMap<string, FacetCountDistribution>;
+ export type Facets = { [key: string]: FacetCountDistribution };
+ private readonly _facets: Facets;

console.log(JSON.stringify(result.facets));

{"author":{"_counts":[],"_stats":{"_avg":4.5,"_count":0,"_max":0,"_min":0,"_sum":0}}}

How best to test these changes

• Existing unit tests

Issue ticket number and link

closes #248

[github-actions[bot]]

:tada: This PR is included in version 1.0.0-beta.34 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket:

[github-actions[bot]]

:tada: This PR is included in version 1.0.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket: