Add EntryPointFilePath MSBuild property

[jjonescz]

Needed for dotnet/roslyn#82944.

[Copilot]

Pull request overview

Adds a new EntryPointFilePath MSBuild property for file-based programs (e.g., dotnet run Program.cs) and makes it available to Roslyn analyzers, addressing the need described in dotnet/roslyn#82944.

Changes:

• Emit <EntryPointFilePath> into the generated virtual project for file-based programs.
• Mark EntryPointFilePath as a CompilerVisibleProperty so it flows into analyzer config options during MSBuild builds.
• Include build_property.EntryPointFilePath in the generated editorconfig used by the csc-only file-based compilation path, and update tests accordingly.

Reviewed changes

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

File	Description
test/dotnet.Tests/CommandTests/Run/RunFileTests.cs	Updates expected virtual project XML to include <EntryPointFilePath> for run-api tests.
src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.Analyzers.targets	Exposes EntryPointFilePath to the compiler/analyzers via CompilerVisibleProperty.
src/Microsoft.DotNet.ProjectTools/VirtualProjectBuilder.cs	Writes <EntryPointFilePath> into the virtual project’s initial PropertyGroup.
src/Cli/dotnet/Commands/Run/CSharpCompilerCommand.Generated.cs	Adds build_property.EntryPointFilePath to the generated editorconfig for the csc-only path.