610 atol and rtol cannot be specified in solver options

[augeorge]

torchdiffeq uses rtol and atol as separate arguments - i.e. torchdiffeq(rtol, atol, method, solver_options).
this PR exposes those arguments in the sampling, calibration, and optimization (ouu.py) functions in interfaces.py as well as adds tests.

• added rtol and atol arguments to sample, calibration, and optimize interfaces
• added test cases for sample, calibration, and optimization using different rtol and atol values.

[augeorge]

@djinnome

[djinnome]

This also adds atol and rtol parameters to ensemble_calibrate and ensemble_sample

[SamWitty]

Rather than have atol and rtol be separate arguments, could we extract them from solver_options if they're available?

[augeorge]

Rather than have atol and rtol be separate arguments, could we extract them from solver_options if they're available?

@djinnome @SamWitty atol and rtol have been moved into solver_options

[djinnome]

Looks good to me. Thanks @augeorge