Implement the v2 capability of calculating/returning wind speed values from specified points in the flow field

[bayc]

Is your feature request related to a problem? Please describe.
In FLORIS v2, the users could supply a set of points to calculate_wake to have the wake model executed at.

Describe the solution you'd like
I'd like to see a similar functionality developed for FLORIS v3.

Describe alternatives you've considered
Continue using v2, but this isn't desired.

Additional context
None currently.

[rafmudaf]

An alternative that might be considered is to add turbines as points to be calculated but not add their effect into the flow field. This is the same as done in the visualization method introduced in #418.

[rafmudaf]

This was introduced in #650