Add setting to adjust kubo log level

[karlrez]

Addresses #2294

Added option to change kubo log level in the settings page.
On startup the log level will be read from local storage and applied to kubo. Log level is set to error level by default.
On startup subsystems are also read from kubo, to be used to validate user input.

Apply log level to all subsystems:
debug
all=debug
*=debug

Or apply specific log level to subsystems:
debug, gc=info, autotls=warn

Form validation checks:

• Log level is valid option: 'debug' , 'info' , 'warn' , 'error' , 'dpanic' , 'panic' , 'fatal'.
• Subsystem is valid option.

Valid input:

Error highlight with placeholder:

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