`plot_coherence_matrix`: split image and matrix windows (#1493)

* plot_coherence_matrix: split image and matrix windows

* cli/plot_coh_matrix: comment out mpl_disconnect to be consistent with cli/tsview.py.

* more comment & rm redundant code

* show lat/lon info in the terminal whenever it's available

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Co-authored-by: Zhang Yunjun <yunjunz@outlook.com>
Co-authored-by: sourcery-ai[bot] <58596630+sourcery-ai[bot]@users.noreply.github.com>