Add a global verbose option

[konstin]

Debugging https://github.com/PyO3/maturin/discussions/2079 i realized that we currently require RUST_LOG for users to debug issues like missing inclusions. I added a global counting -v flag to allow users to get more verbose logging from maturin to help them diagnose their problems.

We currently use -v to configure cargo verbosity level. For simplicity, it now configures both at the same time. Fine-grained control is still possible by setting RUST_LOG.

The levels:

• Default: Show build information and cargo build output.
• -v: Use cargo build -v.
• -vv: Show debug logging and use cargo build -vv.
• -vvv: Show trace logging.

This can be extended to support a quiet option.

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