Calculate overwater area for HBLL survey grids

[jdunic]

Include comparison to HBLL INS grid overwater areas used in synoptic report and elsewhere

Question: The resulting data file is bigger than expected ~ 2 Mb and I don't know why. This is with just an area column added. Not sure if there is a way to fix this that I am missing.

More notes:

• I think the old overwater area HBLL INS grid was missing cells that this one contains
• There are a few discrepancies in total overwater area, but I think the version made in this PR is correct (based off visual inspection)
• Using plotly makes it easier to zoom into and inspect grid and coastline polygon overlap: HBLL INS example
• The survey block object could be returned as the one cropped to the BC coastline but the added polygon complexity makes the object quite large (though it can be simplified using st_simplify(), but it is probably best that users just see the source file for this dataset and crop as they need.

[seananderson]

Thanks, can you add ggplot2 to 'Suggests' in the DESCRIPTION file and then check for ggplot2 in the example section, similarly to how sf is done? https://github.com/pbs-assess/gfdata/actions/runs/9686712894/job/26729747347?pr=18#step:9:220