Test `get_td_waveform` method.

[vaishakp]

Test the functionality to compute polarizations from modes data.

Observations:

1. Apart from a coordinate rotation by pi/2 (this has not been added implicitly yet as it is immediately not clear if the rotation angle is the same across NR catalogs.), the waveform polarizations are differing with a mismatch of up to 1.5% w.r.t. the lal counterparts.

Case study: GT0001

1. The raw individual waveform modes loaded by nrcatalogtools, waveformtools and LAL are the same, upto numerical precision errors.

2. The individual waveform modes after resampling at user specified time-step, but before obtaining polarizations differ with a mismatch of about 0.7%. The plots (1) below show the differences in the (2,2) modes, after they have been suitably aligned in time, phase.

(if the image labels are not visible, please try turning off dark mode.)
3. The mismatches after obtaining the polarizations are about 1.3%.

[prayush]

@vaishakp is this bug still outstanding?