query parameter names for NuGet search requests are not case-insensitive

Fallout from NEXUS-12028: The request log from that ticket suggests that NuGet searches employ case-insensitive query parameters, i.e. /FindPackagesById()?Id=foo vs /FindPackagesById()?id=foo. Our current code however expects case-sensitive query parameters (cf. https://github.com/sonatype/nexus-internal/blob/84a2d0537cb61ea16318e2748019f197bfb6b800/private/plugins/nexus-repository-nuget/src/main/java/com/sonatype/nexus/repository/nuget/odata/ODataUtils.java#L127). This leads to wrong database queries if the parameter case in the request doesn't match the code's expectations, e.g.

• select from asset where (LOWER(attributes.nuget.id) = :p0) and (bucket=#25:0) ORDER BY attributes.nuget.download_count DESC, id asc, version asc, parameters: [p0=foo] vs
• select from asset where (bucket=#25:0) ORDER BY attributes.nuget.download_count DESC, id asc, version asc, parameters: [] (missing id criteria)