[NPM Packaging] AAReviewLambda I do not contain any git commands

[gowoons]

Tech steps

• Create a git folder in src/common
• Create functions for git commands (now in src/review/prompt/gitCommand.ts)
• Create a function that uses the github env variables and returns a list of objects of type {fileName:string, fileContent:string, changedLines: string}
• (Write tests for these functions ?)
• In global index.ts, in case "review", call the git function first, and pass in the list of objects in the review function