Fix inconsistencies between generated product and product specifications

[vbrancat]

This PR resolves the metadata inconsistencies between the generated CSLC-S1 and static layers products with the corresponding product specification documents.

Particularly the PR applies the following fixes:

1. y_spacing will be a positive value
2. added azimuth_solid_earth_tides to the QA stats group
3. Add description to projection metadata field.
4. Correct units of azimuth_steering_rate
5. Correct orbit_type description

• [Testing and check that the above has been addressed according to the received comments ]

[jshimada47]

If the Y-direction is positive going north, shouldn't _yspacing be negative if the records are ordered from north to south?

[vbrancat]

@jshimada47 totally agree with that. However, comments from our CSLC-S1 product review mention that a negative spacing is not intuitive for users :s. I am not sure where the confusion is, frankly

[jshimada47]

Yes, I don't think that it's unusual for geocoded products to have negative y-spacings because most of them define the positive direction as increasing latitude. I'm concerned that using positive-valued y-spacings contradicts the definition in the product spec.

[vbrancat]

@seongsujeong can you please have a look at this PR? Thanks.