Update example notebooks for new pystac-client features

[TomAugspurger]

This is an update that touches every notebook using pystac-client to use the new modifier feature.

In general, every example should access data through STAC, and should access the Planetary Computer's STAC API using a client created with

catalog = pystac_client.Client.open(
    "https://planetarycomputer.microsoft.com/api/stac/v1",
    modifier=planetary_computer.sign_inplace,
)

I'm going to sync this update with an update to the Planetary Computer Hub's container images.