Modernize all C# code snippets

### Describe the issue or suggestion

Prep work for https://github.com/dotnet/dotnet-api-docs/issues/10722.

- [x] Upgrade target framework to .NET 10 (example: https://github.com/dotnet/dotnet-api-docs/pull/12654/changes#r3293816438)
- [ ] Modernize C# code - for example, see remarks at https://github.com/dotnet/dotnet-api-docs/pull/12700#pullrequestreview-4428371172
- [x] System namespace
- [x] System.CodeDom
- [x] System.CodeDom.Compiler
- [x] System.Collections
- [x] System.Collections.Concurrent
- [x] System.Collections.Generic
- [x] System.Collections.Immutable
- [x] System.Collections.ObjectModel
- [x] System.Collections.Specialized
- [x] System.ComponentModel
- [x] System.ComponentModel.Composition
- [x] System.ComponentModel.Composition.Hosting
- [x] System.ComponentModel.Design
- [x] System.ComponentModel.Design.Serialization
- [x] System.Configuration
- [x] System.Data
- [x] System.Diagnostics
- [x] System.Diagnostics.CodeAnalysis
- [x] System.Diagnostics.Contracts
- [x] System.Diagnostics.Eventing.Reader
- [x] System.Diagnostics.SymbolStore
- [x] System.Diagnostics.Tracing
- [x] System.Drawing
- [ ] System.Drawing.Design
- [ ] System.Drawing.Drawing2D
- [ ] System.Drawing.Imaging
- [ ] System.Drawing.Printing
- [x] System.Dynamic
- [ ] System.Globalization
- [ ] System.IO
- [ ] System.IO.Compression
- [x] System.IO.Enumeration
- [ ] System.IO.IsolatedStorage
- [ ] System.IO.MemoryMappedFiles
- [ ] System.IO.Packaging
- [ ] System.IO.Pipes
- [ ] System.IO.Ports
- [ ] System.Linq
- [ ] System.Linq.Expressions
- [ ] System.Media
- [ ] System.Net
- [ ] System.Net.Http
- [ ] System.Net.Mail
- [ ] System.Net.NetworkInformation
- [ ] System.Net.Security
- [ ] System.Net.Sockets
- [ ] System.Numerics
- [ ] System.Printing
- [ ] System.Reflection
- [ ] System.Reflection.Context
- [ ] System.Reflection.Emit
- [ ] System.Reflection.Metadata
- [ ] System.Reflection.Metadata.Ecma335
- [ ] System.Reflection.PortableExecutable
- [ ] System.Resources
- [ ] System.Resources.Tools
- [ ] System.Runtime
- [ ] System.Runtime.CompilerServices
- [ ] System.Runtime.InteropServices
- [ ] System.Runtime.Remoting
- [ ] System.Runtime.Serialization
- [ ] System.Runtime.Versioning
- [ ] System.Security
- [ ] System.Security.AccessControl
- [ ] System.Security.Cryptography
- [ ] System.Security.Cryptography.X509Certificates
- [ ] System.Security.Cryptography.Xml
- [ ] System.Security.Policy
- [ ] System.Security.Principal
- [ ] System.Security.RightsManagement
- [ ] System.ServiceProcess
- [ ] System.Text
- [ ] System.Text.RegularExpressions
- [ ] System.Threading
- [ ] System.Threading.Tasks
- [ ] System.Threading.Tasks.Dataflow
- [ ] System.Timers
- [ ] System.Transactions
- [ ] System.Web.Services
- [ ] System.Web.Services.Configuration
- [ ] System.Web.Services.Discovery
- [ ] System.Web.Services.Protocols
- [ ] System.Xml
- [ ] System.Xml.Linq
- [ ] System.Xml.Schema
- [ ] System.Xml.Serialization
- [ ] System.Xml.XPath
- [ ] System.Xml.Xsl
- [x] Search for ".NET Framework" text in .cs files

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[Associated WorkItem - 601755](https://dev.azure.com/msft-skilling/Content/_workitems/edit/601755)