Add support to TestProjectOptionsDefault to specify projects region

[ocofaigh]

Code is currently picking a random region:

Can we allow user to optionally pick a region which would override the random selection logic?

[daniel-butler-irl]

The region can now be manually set, if omitted it selects a random region. Do you also want to be able to pass a list and randomly select from it?

[daniel-butler-irl]

Its actually called location as this is the projects terminology https://github.com/terraform-ibm-modules/ibmcloud-terratest-wrapper/blob/main/testprojects/test_options.go#L46

[ocofaigh]

@daniel-butler-irl No thats cool - My thought was that if there was a region down or something, we could just lock into one. 99% of the time we let is default to the random