WIP: component-base logs: update klog verbosity also at runtime

[pohly]

What type of PR is this?

/kind feature

What this PR does / why we need it:

When applying the logging configuration, verbosity settings in klog were already updated. This is important because legacy klog calls (for example, klog.V.Enabled) use the klog verbosity settings even when a logger is installed.

But when some code changes the verbosity at runtime via fs.Lookup("v").Value.Set("5"), only the component-base logger settings were updated. Now the Set call also updates klog.

Special notes for your reviewer:

The receiver type of the methods gets changed to pointer because:

• None of the reasons for value receiver from https://go.dev/wiki/CodeReviewComments#receiver-type apply (the struct contains a pointer and modifies the underlying value, so pointer better expresses the intent)
• Binding the value to an interface always allocates on the heap anyway, so the pointer receiver gets used.

WIP: needs tests...

Does this PR introduce a user-facing change?

component-base logs: update also klog verbosity when changing verbosity at runtime through command line flags

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This pull-request has been approved by: pohly
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