Don't warn about recursive includes merged from c_cpp_properties.json

[owevertonguedes]

Fixes #14125

Problem

sendCustomConfigurations warned whenever any includePath entry ended in **:

if (item.configuration.includePath.some(path => path.endsWith('**'))) {
    console.warn("custom include paths should not use recursive includes ('**')");
}

Its only caller is provideCustomConfigurationAsync, and when mergeConfigurations is enabled that caller has already appended the includePath entries from the user's c_cpp_properties.json to every configuration returned by the provider. A trailing ** is a supported way to recurse there, so the warning fired for paths the configuration provider never supplied.

Change

Move the check ahead of that append, so it only ever sees the provider's own include paths. The warning for a provider that really does use ** is unchanged, with or without mergeConfigurations.

The check now runs before isSourceFileConfigurationItem validates each item, so it is guarded by configs instanceof Array and util.isArrayOfString(...) to keep the same tolerance for malformed third-party data. It also sits after deepCopy, so when merging it reads the same normalized copy the existing merge loop reads.

Testing

I drove provideCustomConfigurationAsync against the compiled extension with a stub provider and compared every case to main:

** comes from	mergeConfigurations	before	after
c_cpp_properties.json only	on	warns	no warning
the provider	on	warns	warns
c_cpp_properties.json only	off	no warning	no warning
the provider	off	warns	warns

I also checked malformed provider input that the pre-patch code tolerated, so the earlier validation is not skipped: an includePath that is not an array, an array-like object instead of an array, and a falsy first element all behave exactly as they did before.

One difference worth flagging: an item that carries a recursive include and fails validation for an unrelated reason now produces the recursive-include warning in addition to the existing "discarding invalid SourceFileConfigurationItem" one, because the check no longer sits behind that validation. Both are console.warn diagnostics for provider authors and neither item is sent either way, but I can restrict the check to fully valid items if you would rather keep that exact.

tsc --build, eslint src test ui .scripts, the unit suite (193 passing) and git diff --check are all clean. I could not run the SimpleCppProject integration suite, which is where a regression test for this would belong, because it needs the native binaries and I have no way to run it here, so I did not add a test I could not execute.

[Copilot]

Pull request overview

This PR fixes an incorrect provider diagnostic that was triggered when mergeConfigurations appended includePath entries from c_cpp_properties.json (where a trailing ** is valid) into configurations supplied by a custom configuration provider.

Changes:

• Moves the “recursive include” (**) warning so it runs before merging c_cpp_properties.json include paths into provider configs.
• Removes the same warning from sendCustomConfigurations, ensuring only provider-supplied include paths are evaluated.

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