Use M.Q.Convert.DoubleAsStringWithPrecision to trim Doubles printed in the katas

[tcNickolas]

Follow-up to #1406: now that the function M.Q.Convert.DoubleAsStringWithPrecision is available, we can use it in the katas to shorten the long floating-point numbers.

Here are a few examples of the katas that print long doubles:

• Complex Arithmetic
• Single-Qubit Gates kata, task "Prepare Arbitrary State"
• Preparing Quantum States, task "Unequal Superposition"

There are probably others; the typical scenario in which this occurs is printing the Double parameters of the test or returns of the solution for an incorrect solution. We are unlikely to need more than 2-3 digits of precision in these cases.

[devikamehra]

@tcNickolas I would like to work on this

[tcNickolas]

@devikamehra Sounds great! It should be very straightforward, but let us know if you have any questions