Add common layers for the crawl, keyphrase, and socket applications

[ashley-evans]

Value Added

Completes transition from old project structure to new monorepo structure using lerna. Reduces code duplication.

Description

As part of #55 a common crawl layer was introduced that contained common code that was used across all of the crawl lambda functions.

Similar duplication exists across the remaining applications, specifically in each of the function's constants.js file. Therefore, similiar changes should be made to reduce the code duplication further.

Acceptance Criteria

AC01

• Update each of the remaining applications with their own common layers that contain all common code used across that application.

AC02

• Update socket application template to use crawl common layer for obtaining crawl constants rather than duplicating code.

AC03

• Changes required to ensure the lambda functions continue to function should be achieved by SAM/CloudFormation template updates