feat: add support for access token generation and validation

[mrchocha]

Context

• This PR contains feature to create and validate access tokens (stored in broker) via SDK

Issue & Relevant PRs

• This enhancements will be subpart of following issue
  1. Feature Request: Support in Access keys as a second authentication method memphis-rest-gateway#51
• Following are relevant PRs
  1. feat: add support for access token storage and REST handlers memphis#1342
  2. feat: add support for access token generation and authentication memphis-rest-gateway#53

Examples

Create New Access Token via SDK

Method

generatedTokenData, err := conn.GenerateAccessToken(username, body.Description)

Output

AccessToken{
   AccessKeyID:  "string",
   SecretKey:   "string",
}

Validate Access Token via SDK

Method

isValid, err := conn.ValidateAccessToken(accessKeyId, secretKey)

isValid is true if valid accessKeyId and secretKey is valid or false if invalid