Introduce Deal search

[TSMMark]

Hi, thanks for maintaining this awesome gem

I wanted to be able to search deals by name and pipeline, and this functionality was missing from the gem (AFAICT), even though it looked supported by the objects v3 search API

Originally found this discussion here: https://community.hubspot.com/t5/APIs-Integrations/How-can-I-do-a-search-for-all-deals-in-the-default-pipeline/m-p/793111 which led to the v3 search docs here: https://developers.hubspot.com/docs/api/crm/search

I've got this working, can be searched and filtered like so:

deals = Hubspot::Deal.find_by_search(
  properties: %w(dealname amount closedate dealstage),
  filters: [
    { propertyName: 'pipeline', 'operator': 'EQ', value: '12345' },
    { propertyName: 'dealname', 'operator': 'CONTAINS_TOKEN', value: 'MyDealName' },
  ],
)

Unfortunately the search API seems to return results in a very different format from the v1 API that was currently being used to fetch deals, so I had to strip out some of the associations from being required for deal init.

Let me know if you would accept a PR like this, what tests you would need, anything else you'd change about the way I'm doing this lmk

[fonji]

Looks very cool, thank you!
Could you add tests for .find_by_search?