Making the k6/experimental/redis module part of the k6 core

[oleiade]

A few releases back, we introduced the k6/experimental/redis module to k6.

Experimental modules intend to become part of the core eventually. Although the module has been around for a while, we have yet to take the opportunity to take a step back and consider what is left to do to reach a state acceptable to become a core module.

Left to address

Beta Give feedback

1. k6/Cannot run redis load test in cluster mode #3081
2. xk6-redis/#16
3. xk6-redis/#13
4. xk6-redis/#14

Once those tasks are addressed, the Redis module should be in a good enough state to be considered stable (unless some other major issue occurs in the meantime).