Provide expected sample rate, max buffer size, and slimmable size as optional parameters to `get_dsp()`

[sdatkinson]

Allow for specifying ☝🏻 when calling get_dsp() so that the model can be loaded directly as-expected without needing to call methods to re-configure (i.e. Reset() and SetSlimmableSize()).

Context: #266 (comment) (and above)

[mikeoliphant]

I just thought of one more option for handling this - add a "supress prewarm" call that prevents any prewarming from happening until prewarm is called manually. Basically a way for the caller to say "I'm going to change several things in series that are going to require prewarming afterward".

Actually, this could be useful even if you make the get_dsp() change.

[sdatkinson]

Totally. Cut me another Issue for this?

[mikeoliphant]

Totally. Cut me another Issue for this?

Done: #270