Make profile flag optional

[jamnew]

When already in an authenticated session or subshell e.g. when using aws-vault the profile flag is not needed. Additionally this package assumes that .aws/credentials is used but this is not always the case e.g.

Action download initiated For ALL Function(s) from /source/path/
error Error: Command failed: aws lambda --profile my-admin list-functions

The source profile "my-admin" must have credentials.

    at genericNodeError (node:internal/errors:983:15)
    at wrappedFn (node:internal/errors:537:14)
    at ChildProcess.exithandler (node:child_process:421:12)
    at ChildProcess.emit (node:events:520:28)
    at maybeClose (node:internal/child_process:1105:16)
    at ChildProcess._handle.onexit (node:internal/child_process:305:5) {
  code: 255,
  killed: false,
  signal: null,
  cmd: 'aws lambda --profile my-admin list-functions'
}

This can all be improved by making profile flag optional. I have already made the change in code and can submit a pull request if you like?