Prevent activating an already activated loans market

[daniel-savu]

The activate_market extrinsic should fail if the market is already active, so as not to re-emit the ActivatedMarket event.

[nakul1010]

Solutions

Solution 1: Add an is_active flag when updating mutate_market

Pros:

• Allows updating the mutate_market function to include an is_active flag.
• Only emits an event if the flag is not set, reducing unnecessary event emissions.

Cons:

• If additional conditions need to be checked in the future, adding more flags can cause issues and make the code more complex.

Solution 2: Add the check_market_state_before_activating function

Pros:

• Introduces a separate function, check_market_state_before_activating, to ensure all necessary checks are performed before updating the market.

Cons:

• Time complexity increases

Solution 3: Update mutate_market to accept result

Pros:

• Time complexity remains the same as that of the existing solution.