Draft: Introduce new test scenario config (and upgrade to k6 0.27.x)

Closes #319 #298 (closed)

MR looks to improve the options selection process (i.e. configuring how tests should be run against environments), making it more straightforward (in design and code) and getting rid of the many options files as is the case today. This is achieved by just configuring what the environment should be expected to handle in the Environment Config file instead.

Option files will be removed but a form of backwards compatibility is provided by parsing the options filename is passed (along with appropriate warnings).

For the new solution, k6's new implementation of scenarios was used here and as such, the MR also brings in an update to the latest k6 version - 0.27.1.