[eodag server]: no error on bbox and intersects together in post search request's body

[sandeep-vidyapu]

Describe the bug
I have two issues with the post search request as described below:

1. While searching the STAC using post request with the body containing both, "bbox" and "intersects", I am supposed to receive 400 bad request error (source: https://github.com/radiantearth/stac-api-spec/tree/main/item-search).
   But, I am not receiving any such error, but getting rendered with the items.
   So, can you please look into it.

2. In eodag/eodag/rest/utils.py (https://github.com/CS-SI/eodag/blob/develop/eodag/rest/utils.py#L274C2-L281C44), there seems to be a checking on an attribute "geom" which was not part of STAC spec.
   So, can you please look into it.

Code To Reproduce
CLI commands or Python code snippet to reproduce the bug. Please use maximum verbosity using:

body = {
        "bbox": [
                -110,
                39.5,
                -105,
                40.5
        ],
        "datetime": "2018-02-12T00:00:00Z/2018-03-18T12:31:12Z",
        "intersects": {
                "type": "Point",
                "coordinates": [
                        0,
                        0
                ]
        },
        "limit": 100
}
resp = requests.post("http://localhost:8000"+"/stac/search", json=body)
print(f"\n\n{resp.text=}")

Output
Compete output obtained with maximal verbosity.

Environment:

• Python version: Python 3.8.10
• EODAG version: eodag (Earth Observation Data Access Gateway): version 2.10.0

Additional context