[ENH] Make AutoETS more configurable

[TonyBagnall]

Describe the feature or idea you want to propose

we should allow the user to turn searching seasonal additive/multiplicative etc on or off, and default to not search multiplicative
#3297

Describe your proposed solution

I would like to align with the smooth, with flags for the following, although maybe not character based

https://github.com/config-i1/smooth/blob/48c389121fefde1f0e75657a467ce9d071353240/python/src/smooth/adam_general/core/es.py
model : Union[str, List[str]], default="ZXZ"
The type of ETS model. The first letter stands for the type of error
("A" or "M"), the second for trend ("N", "A", "Ad", "M" or "Md"),
and the third for seasonality ("N", "A" or "M").

    Examples: "ANN", "AAN", "AAdN", "AAA", "AAdA", "MAdM"

    Special codes:
    - "ZZZ": Automatic selection using information criteria
    - "XXX": Select only additive components
    - "YYY": Select only multiplicative components
    - "ZXZ": Auto-select error and seasonal, additive trend only (default)
    - "CCC": Combination of all models using AIC weights

Describe alternatives you've considered, if relevant

No response

Additional context

No response