Search with cop_ads not working for CAMS_SOLAR_RADIATION

[jlahovnik]

Describe the bug
When you execute a search for CAMS_SOLAR_RADIATION, it fails with provider cop_ads.

Code To Reproduce
dag.search(productType="CAMS_SOLAR_RADIATION", provider="cop_ads")

Output
File "/home/julia/.local/lib/python3.10/site-packages/eodag/api/core.py", line 1856, in _do_search
res, nb_res = search_plugin.query(prep, **kwargs)
File "/home/julia/.local/lib/python3.10/site-packages/eodag/plugins/search/build_search_result.py", line 430, in query
result, num_items = super().query(prep, **kwargs)
File "/home/julia/.local/lib/python3.10/site-packages/eodag/plugins/search/qssearch.py", line 1561, in query
qp, _ = self.build_query_string(product_type, **keywords)
File "/home/julia/.local/lib/python3.10/site-packages/eodag/plugins/search/build_search_result.py", line 454, in build_query_string
available_properties = {
File "/home/julia/.local/lib/python3.10/site-packages/eodag/plugins/search/build_search_result.py", line 456, in
k: strip_quotes(v)
File "/home/julia/.local/lib/python3.10/site-packages/eodag/plugins/search/build_search_result.py", line 248, in strip_quotes
raise NotImplementedError("Dict value is not supported.")

Additional context
strip_quotes function has to be updated to support dicts