Add a standalone slope filtering pipeline and update bbox parsing

[cmspeed]

This PR adds a standalone pipeline for generating slope-filtered versions of DIST-HLS and RTC products (opera-disaster slope-filter). The output is identical to the opera-disaster run when -m landslide and -st are specified; however, the key difference is the input to the slope filtering are either (1) local OPERA DIST-HLS / RTC granules or (2) local OPERA DIST-HLS / RTC mosaics. The standalone slope filtering automatically obtains B10_DEM.tif layers covering the AOI from the OPERA DSWx-HLS and generates a dem.tif and slope.tif. The slope.tif is used to mask pixels less than -st.

This PR also standardizes bounding box parsing across the CLI (i.e., run, search, download, mosaic)

Changes

• Implemented run_slope_filter_only to generate slope-filtered outputs within a local directory.
• Implemented apply_slope_mask_to_raster to dynamically reproject the slope.tif mask to match any target raster's specific grid in-memory, ensuring slope filtering can be done on both individual granules and mosaics.
• Implemented fetch_missing_dems to ensure all DEMs (from DSWx-HLS, band 10) are downloaded to the local directory before proceeding.
• Refactored get_local_spatial_properties to extract CRS and bounds directly from raster headers usingrasterio, rather than relying on OPERA text metadata.
• Standardized bounding box parsing using a new parse_bbox_input helper.
• Standardized the mosaic command's input flag from -i to -ld for CLI consistency.

How to run

Here is a scenario for which the standalone slope filtering could be applied.

(1) Download DIST-HLS / RTC granules locally:

opera-disaster download -b Brazil_DaNCE_AOI.kml -d 2024-05-08/2024-05-15 -m landslide -o testing-sf

(2) Create daily mosaics from the input granules:

opera-disaster mosaic -b Brazil_DaNCE_AOI.kml -ld testing-sf/data -o testing-sf/data/mosaics

(3) Apply a slope filter to the mosaics and save the new outputs in a subdirectory:

opera-disaster slope-filter -ld testing-sf/data/mosaics -o testing-sf/data/mosaics/slope_filtered -st 8