Change the way ProphetModel works with regressors

[julia-shenshina]

🚀 Feature Request

Change models behavior in work with regressors

Motivation

New way of work with regressors.

Proposal

• Change _ProphetModel.fit:
  • add arg regressors: Optional[List[str]] = None: all the given columns should be added to model as regressors
  • change this loop:
    • logic of cap and floor should be deleted
    • we understand that column is regressor not with prefix regressor but with x in regressors
• Change _ProphetModel.predict:
  • logic of cap and floor should be deleted
• Change ProphetModel.fit:
  • now it should get list of regressors names from ts and pass it to self.models.fit

Test cases

No response

Alternatives

No response

Additional context

No response

Checklist

• I discussed this issue with ETNA Team

[julia-shenshina]

is blocked by #327 #326 #328