Knox Token Generation UI should have Validation checks for invalid lifetimes

Problem Description:

The Token Generation UI should validate invalid lifetimes and throw "Invalid Lifetime" warning message.

Following are the conditions to have Validation Check for [D,H,M]:

• Check with -ve values
• Check with decimal values
• Check with empty values
• Check Integer MAX value

PS: Currently, it gives invalid lifetime warning only when D,H,M are all set to 0.