Add qFSP boundary mask to RSLC

[bhawkins]

This PR implements the inputDataExceptionMask in RSLC products for the LSAR qFSP-related exception codes. It handles all six possible qFSP exception codes. For now, the strategy to is locate the peaks of the AC table weights in the EL angle domain and use the EL-angle LUT to generate the mask. This mask is in the raw data domain, so it's resampled to the RSLC grid using reskew LUTs. (These could be used to reskew other tables in some future PR, too). I added a vectorized LUT2d::eval overload to make this faster.

Eyeballing the plots for the case I tested on, I'm not sure the mask covers everything where there's obvious residual phase. So maybe instead of defining the overlap region as peak-to-peak, we should be more conservative and use a -6 dB threshold or something. I hope folks can do some InSAR tests to help figure out the best approach.

Note that the mask is populated based on the contents of the input L0B hasInputDataException flag, so that must be populated to see any effect.

Another question is what to do about mixed-mode frames where one L0B has a qFSP slip and its neighbor doesn't. For now, the qFSP overlap region is marked invalid for the entirety of the output product.

[bhawkins]

Only got part of the way through this PR in our meeting today. Comments so far:

[bhawkins]

Need to think about the interaction with EAP on/off.

[rad-eng-59]

FYI, L0B processor is using the same integer values for the same purpose for the first 6 fields but with more concise names (see below). Given our L0B process does not process S-SAR, it does not need to cover new fields. However, for the sake of consistency between names, we should perhaps request a change to L-SAR L0B to use the same dataclass. Here is the similar class in the current L0B process:

class QfspOutlierId(Flag):
    """NISAR L-band qFSP outlier identifier w/ bitwise operation"""
    NA = 0
    H0 = auto()
    H1 = auto()
    H2 = auto()
    V0 = auto()
    V1 = auto()
    V2 = auto()

Btw, for bitwise enum.Flag, the auto() will automatically generates the power of 2 values in the ascending order starting from 2^0.

[rad-eng-59]

As discussed in the meeting, you can use Antenna pattern HDF5 product whom used to generate AC table in instrument HDF5. The respective antenna parser will have some very useful methods. For instance, to get EL angle of the peak for all beams and their common AZ boresight angle, AntennaParser has this method handy:

el_peaks, az_boresight = AntennaParser(hdf5file).locate_beams_peak(pol)

FYI, regardless of the EL angle resolution of the patterns, the actual peak locations are locally and precisely estimated in this antenna method. AC table have a EL angle resolution of 50 mdeg.

[rad-eng-59]

Not sure why we need to use S-SARor even RESERVED given they are not properly being handled.

[rad-eng-59]

Perhaps one can check for EAP and if it is OFF issue a warning that the mask values can be invalid due to EAP=OFF.
I suggest we simply generate a qFSP sample-slip mask when EAP=True which also guarantees that both antenna and instrument HDF5 are available. In case of EAP=False, a warning is issued w/ empty dataset.

[rad-eng-59]

LGTM. Thanks.
The code still doesn't warn or handle the case when EAP=False.
I wonder what is the decision on that. I did put my suggestion in the comment earlier.