Implement tests for DEX Module LP command: createPool

[emiliolisk]

Description

createPool was tested with the following scenarios and expectations as mentioned below:

Scenario	Expectation
Should be successful when all the parameters are correct	Calls token methods and emits poolCreated, positionCreated events.
Should fail when tokenID0 and tokenID1 are not sorted lexicographically	Exception is thrown.
Should fail when amount0Desired or amount1Desired are zero	Exception is thrown.
Should fail when tickLower and tickUpper do not meet requirements	Exception is thrown.
Should fail when header.timestamp > maxTimestampValid	Exception is thrown.

Acceptance Criteria

• Existing and new unit tests are passing

[Naureen1lightcurve]

This issue #270 is already resolved and the last modification is in this commit.