feat(): working on nested fields

Change Type

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[ ] Change Request
[ ] Bug Fix
[x] New Feature
[ ] Documentation

Breaking Changes

Does your pull request introduce breaking changes?

[x] Yes, this pull request will introduce breaking changes
[ ] No, no breaking changes will be introduced

Description

This PR brings the ability to work with nested fields for sources. Like it gives us an ability to consume data from various APIs and query structures like

{
   "data":{
      "array":[
         1,
         3,
         1
      ],
      "obj":{
         "name":"example"
      }
   }
}

Also, Mongodb snapshot streaming improvements. Added snapshot event type so we can use sink batch inserts for mongodb or postgresql to perform initial load faster

Testing

Describe how you have tested the changes or how we should test the changes:

[x] I have added new tests for my changes
[x] I have successfully run and passed all tests with my changes locally
[ ] I have not added any testing

Checklist

Please confirm the following:

[x] I have made sure all new and existing tests passed
[ ] I have updated any necessary documentation
[x] I have ensured all commits are neat and tidy

Reviewers

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Additional context

This PR also brings some small performance issues, like redundant JSON marshaling and unmarshaling for certain data Sources. I'm going to fix that later

Tests performed

During the testing, I checked the following combinations:

Postgres -> Postgres (snapshot, update, delete, insert)👌🏻  
Postgres -> MongoDB (snapshot, update, delete) 👌🏻 
WebSockets -> MongoDB  (upsert by default)👌🏻

usedatabrew / blink