Add support for Named Saved Queries

[bitner]

Add support for named saved queries that can contain relative datetime parameters to enable saving a query for example that would fetch all items for year-to-date.

[vincentsarago]

would the search hash be used for that?

in _search_query we can already pass additional metadata for a search query which we make use in titiler-pgstac to add name and other user defined fields https://github.com/stac-utils/titiler-pgstac/blob/main/titiler/pgstac/factory.py#L725-L731

We can use the name then to filter the searches like https://raster.eoapi.dev/searches/list?name=Yellowstone%20Mosaic https://github.com/stac-utils/titiler-pgstac/blob/main/titiler/pgstac/factory.py#L882-L893