[Feature] : Added Custom EnvVars support

[sadath-12]

Fixes #630

Type of change

You can now add extra env field under to spec to configure additionalEnvs
For ex: under Spec section you can add ``` env:

• name: CUSTOM_ENV_VAR_1
  value: "custom_value_1"
• name: CUSTOM_ENV_VAR_2
  value: "custom_value_2" ```

• New feature (non-breaking change which adds functionality)

Checklist

• Tests have been added/modified and all tests pass.
• Functionality/bugs have been confirmed to be unchanged or fixed.
• I have performed a self-review of my own code.
• Documentation has been updated or added where necessary.

Additional Context