add warning message when using x fix

[nivekithan]

Fix for issue: #155545

Before:

After:

Text added

WARNING: `x fix` is provided on a best-effort basis and does not support all `cargo fix` options correctly.

[rustbot]

This PR modifies src/bootstrap/src/core/config.

If appropriate, please update CONFIG_CHANGE_HISTORY in src/bootstrap/src/utils/change_tracker.rs.

[rustbot]

r? @clubby789

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• Owners of files modified in this PR: bootstrap
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