Fix command-line binlog replay to respect minimum reader version

[Copilot]

Fixes #(issue number needed)

Context

MSBuild throws fatal exceptions when replaying binlog files with format versions newer than supported, even when the minimum required reader version is within range. The minimum reader version field exists precisely to enable forward compatibility—older MSBuilds should read (possibly partial) logs from newer versions.

Example failure:

❯ dotnet msbuild newer.binlog
There was an exception while reading the log file: The log file format version is 26 with minimum required reader version 18, whereas this version of MSBuild only supports versions up to 25.

Changes Made

XMake.cs:

• Enable AllowForwardCompatibility on BinaryLogReplayEventSource
• Subscribe to RecoverableReadError for graceful error handling
• Use BinaryReader overload to ensure compatibility flag is respected
• Emit warning (non-fatal) when file version exceeds supported version but minimum reader version is compatible

BinaryLogger.cs:

• Make FileFormatVersion constant public (was internal) for version comparison

BinaryLogger_Tests.cs:

• Add tests for AllowForwardCompatibility property and public FileFormatVersion access

Testing

Verified with simulated binlog files:

• Format v26, min reader v18: Warning displayed, replay succeeds
• Format v26, min reader v26: Error displayed, replay fails (correct)
• Format v25 (current): No warning, normal operation

Unit tests pass for new API surface.

Notes

Pre-existing test failures in BinaryLogger_Tests are unrelated (confirmed on base commit).

Original prompt

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This section details on the original issue you should resolve

<issue_title>Command-line log replay is too aggressive about versioning</issue_title>
<issue_description>```sh-session
❯ dotnet msbuild -flp:v=diag -noconlog /Users/raines/Downloads/CentralNode_devenv_PID=38240_x64_BuildManager_DesignTimeBatchBuild_0.binlog
There was an exception while reading the log file: The log file format version is 25 with minimum required reader version 18, whereas this version of MSBuild only supports versions up to 23.

That message should definitely be emitted, but it should be nonfatal--the point of the "minimum required reader version" is to allow reading (possibly partial) logs from newer MSBuilds.</issue_description>

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

<comments>
</comments>

• Fixes Command-line log replay is too aggressive about versioning #12254

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