Unify LangVersion to "latest" across projects

[Copilot]

Multiple projects had explicit LangVersion settings that conflicted with or duplicated the repository default of latest in Configuration.props.

Changes

Removed explicit LangVersion declarations from:

• src/Mono.Android.Runtime/Mono.Android.Runtime.csproj — was pinned to 10
• src/Microsoft.Android.Sdk.Analysis/Microsoft.Android.Sdk.Analysis.csproj — redundant latest
• src/Microsoft.Android.Sdk.Analysis/Tests/Microsoft.Android.Sdk.Analysis.Tests.csproj — redundant latest
• build-tools/xaprepare/xaprepare/xaprepare.csproj — redundant $(LangVersion)

All projects now inherit from the central default:

<!-- Configuration.props:48 -->
<LangVersion Condition=" '$(LangVersion)' == '' ">latest</LangVersion>

Out of scope

External submodules (external/Java.Interop, external/xamarin-android-tools) have their own LangVersion settings and should be updated in their respective repositories.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Unify LangVersion to "latest" across projects</issue_title>
<issue_description>### Android framework version

net11.0-android (Preview)

Affected platform version

.NET 11

Description

There are many different C# versions used throught the projects in the repo. It would be beneficial to unify all to latest. Is there anything preventing us from increasing the language version in some case?

Steps to Reproduce

Did you find any workaround?

No response

Relevant log output

```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes Unify LangVersion to "latest" across projects #10765

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

[Copilot]

Pull request overview

This PR standardizes C# language version settings across the repository by removing explicit LangVersion declarations from four project files, allowing them to inherit the default latest setting from Configuration.props.

Changes:

• Removed explicit LangVersion declarations from four project files that either duplicated the repository default or were pinned to older versions
• All affected projects now inherit LangVersion set to latest from Configuration.props line 48

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/Mono.Android.Runtime/Mono.Android.Runtime.csproj	Removed C# 10 version pin, now inherits latest
src/Microsoft.Android.Sdk.Analysis/Microsoft.Android.Sdk.Analysis.csproj	Removed redundant latest declaration
src/Microsoft.Android.Sdk.Analysis/Tests/Microsoft.Android.Sdk.Analysis.Tests.csproj	Removed redundant latest declaration
build-tools/xaprepare/xaprepare/xaprepare.csproj	Removed redundant $(LangVersion) reference