feat: get contact by id endpoint

[tapiarafael]

Proposed changes (including videos or screenshots)

Implemented a new endpoint to retrieve contact info by id.

[GET] api/v1/omnichannel/contacts.get?contactId=123 response example:

{
	"contact": {
		"_id": "123",
		"name": "john doe",
		"emails": [
			"[email protected]"
		],
		"phones": [
			"1-658-751-2622"
		],
		"contactManager": "321",
		"customFields": {},
		"unknown": false,
	},
	"success": true
}

Issue(s)

Steps to test or reproduce

Further comments

SCI-36