Fix IQueryable select projection path

[slorello89]

Issue: #507

Root cause: IQueryProvider.CreateQuery(Expression) was using the full IQueryable<T> type as the collection generic argument and then invoking the internal RedisCollection<T> constructor with public-only reflection, so projected queries failed before enumeration.

Fix: derive the sequence element type from the query expression, invoke the internal constructor with non-public binding flags, and preserve the original document root type on projected collections.

Tests run:

• dotnet test test/Redis.OM.Unit.Tests/Redis.OM.Unit.Tests.csproj --filter FullyQualifiedName~Redis.OM.Unit.Tests.RediSearchTests.SearchTests.TestSelectViaNonGenericQueryProvider --no-restore
• dotnet test test/Redis.OM.Unit.Tests/Redis.OM.Unit.Tests.csproj -f net7.0 --filter FullyQualifiedName~Redis.OM.Unit.Tests.RediSearchTests.SearchFunctionalTests.SelectNameViaNonGenericQueryProvider --no-restore
• dotnet test test/Redis.OM.Unit.Tests/Redis.OM.Unit.Tests.csproj -f net6.0 --filter FullyQualifiedName~Redis.OM.Unit.Tests.RediSearchTests.SearchFunctionalTests.SelectNameViaNonGenericQueryProvider --no-restore

Risk: low. The change is scoped to query-provider instantiation for projected queryables; the main remaining risk is compatibility with other expression shapes that also flow through non-generic CreateQuery.

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Note

Low Risk
Low risk, scoped to RedisQueryProvider.CreateQuery(Expression) instantiation logic for projected queryables; primary risk is unexpected element/root type inference for uncommon expression shapes.

Overview
Fixes projection queries created via the non-generic IQueryProvider.CreateQuery(Expression) path so Select/chained projections no longer fail before enumeration.

The provider now derives the sequence element type from the expression type, uses reflection that can invoke non-public RedisCollection<T> constructors, and preserves the original document RootType on projected collections. Adds unit + functional coverage for selecting Name via manually-built Queryable.Select expressions using the non-generic provider.

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[jit-ci]

🛡️ Jit Security Scan Results

✅ No security findings were detected in this PR

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