update ggcorrmat defaults

[IndrajeetPatil]

• don't default to full matrix (should be "upper"; in "lower", the axes labels are far away from corresponding cells)
• apply p-value adjustment by default ("holm")
• remove grid in the background
• increase the default size for the legend
• support data2 argument? (in this case, the default should be a full matrix; Feature request: allow different set of variables for columns and rows in ggcorrmat #120)
• support partial correlations (adding support for partial correlations in ggcorrmat #64)
• improve caption details
• remove all things p-value when type = "bf"
• print pch in ggcorrmat caption; not just X
• Winsorized r as the robust measure

[IndrajeetPatil]

https://twitter.com/BignardiG/status/1362741125551968260?s=20