[Feature]: DynamoDB Data Accessor Structure for Emily API

[AshtonStephens]

Feature - DynamoDB Data Accessor Structure for Emily API

1. Description

This ticket is to create a data accessor for the emily API that uses dynamodb in the backend. This ticket will include some hardcoded values that will later be replaced with configurations.

1.1 Context & Purpose

Create data accessor for DynamoDB in emily client so that the data can be accessed within the API.

2. Technical Details:

The accessor should be able to handle the three tables and any secondary indices

• chainstate
• withdrawal
  • + withdrawal info
• deposit
  • + deposit info

In this PR the accessor should support all of the following for the tables:

• creating a new entry
• getting an existing entry
• querying for multiple entries

2.1 Acceptance Criteria:

• There's a dynamodb accessor in the PR that can handle the above technical criteria
• The accessor is tested
• There's a PR approved by at least two people
• The PR is merged

3. Related Issues and Pull Requests (optional):