:pencil2: Edit Sentinel-1 preview PNG urls from Planetary Computer

[weiji14]

Need to add &asset_as_band=True to the PNG preview URLs for the Sentinel-1 GRD and RTC images on Planetary Computer now, possibly due to updated Titiler version (see https://planetarycomputer.microsoft.com/docs/changelogs/history#january-2023). Also clarified whether the preview image is Sentinel-1 RTC or GRD, and did the same for the Sentinel-2 L2A preview.

Preview at https://zen3geo--129.org.readthedocs.build/en/129/chipping.html

In case the URLs change again, these are the Planetary Computer explorer links to the Sentinel-1/Sentinel-2 images:

• Sentinel-2 L2A image over Singapore on 20220115 - https://planetarycomputer.microsoft.com/explore?c=103.6957%2C1.3129&z=8.70&v=2&d=sentinel-2-l2a&s=false%3A%3A100%3A%3Atrue&sr=desc&ae=0&m=cql%3Adffe43c8e7b4dfe4d883e0475848ba22&r=Natural+color
• Sentinel-1 GRD image over Johor, Malaysia on 20191215 - https://planetarycomputer.microsoft.com/explore?c=104.0106%2C1.8523&z=7.71&v=2&d=sentinel-1-grd&m=cql%3Aea687c9f9c3f69afa49e900ea3347143&r=VV%2C+VH+False-color+composite&s=false%3A%3A100%3A%3Atrue&sr=desc&ae=0
• Sentinel-1 RTC image over Sumatra Barat, Indonesia on 20220223 - https://planetarycomputer.microsoft.com/explore?c=99.3051%2C0.0538&z=7.71&v=2&d=sentinel-1-rtc&m=cql%3A5c13464ff5995ad7e3b46c5105da5b4c&r=VV%2C+VH+False-color+composite&s=false%3A%3A100%3A%3Atrue&sr=desc&ae=0
• Sentinel-1 GRD image over Osaka, Japan on 20220614 - https://planetarycomputer.microsoft.com/explore?c=135.2645%2C34.0466&z=7.57&v=2&d=sentinel-1-grd&s=false%3A%3A100%3A%3Atrue&sr=desc&ae=0&m=cql%3Ac03c473974ad2a6afca90643c180e49d&r=VV%2C+VH+False-color+composite

Patches #8, #20, #31, #62