Logs the mode and description of keploy

[frey0-0]

Fixes #390

• Adds logs in the constructor of keploy class and mock.ts
• Uses mode.GetMode() to get the mode instead of process.env as the mode in the .env can be some other than test, record or off
• Add a modeDescription() function to log the description as writing a switch case or if there seemed to reduce the readability of the code

[re-Tick]

LGTM