update color scheme

[mratsim]

This is a bikeshedding proposal on a new color scheme.
The most important part is not making NOTICE look like a warning.

In Debug mode

In Trace mode

Opinion:

• The gray might also be used for debug, but I then don't have a good color for trace. White is too eye-catching/bright for a log level as noisy as this.
• DBG and INF might be not contrasted enough which might make us miss INFO level. But blue is kind of taken by the log content.

References:

• [RFC] Rework log levels nimbus-eth2#1779
• Drastically reduce logging verbosity nimbus-eth2#1785
• Revisiting log levels nimbus-eth2#1788

[mratsim]

An update to improve:

• contrast between log-level (Cyan and green are too near)
• tone down the "aggressiveness":
  • green even dark is too bright for info, cyan is better
  • magenta dark for notice instead of light
• trace logs are not meant for console but for file and search via tools so they don't take valuable color space anymore

in debug mode this is how it displays.

[arnetheduck]

notice a bit hard to pick out on a light background.. readable, just not very different from dbg

[mratsim]

For users I think this is OK since they won't run in debug.

I'm not sure what to do now as the other colors are taken (blue for content) or not contrasted enough, cyan (info) vs green.