logconfig: support YAML arrays to configure channels

[jseldess]

PR: cockroachdb/cockroach#59352

From release notes:

• The channels parameter for the log sink configurations now supports a more flexible input configuration format:
  Syntax to include specific channels:
  channels: dev,sessions (yaml string)
  channels: 'dev,sessions' (yaml string, equivalent to previous)
  channels: [dev,sessions] (yaml array, can use multi-line syntax with hyphens too)
  channels: ['dev','sessions'] (same as previous)
  channels: '[dev,sessions]' (bracket-enclosed list inside yaml string)

  Syntax to include all channels:
  channels: all (yaml string)
  channels: 'all' (same as previous)
  channels: [all] (yaml array)
  channels: ['all'] (same as previous)
  channels: '[all]' (bracket-enclosed "all" inside yaml string)

  Syntax to include all channels except some:
  channels: all except dev,sessions (yaml string)
  channels: 'all except dev,sessions' (same as previous, quoted string)
  channels: 'all except [dev,sessions]' (same as previous, list is bracket enclosed)

  For example: sinks: stderr: channels: - DEV - SQL_SESSIONS uses the "native" YAML syntax for lists. [#59352][#59352]

[jseldess]

@taroface, @mikeCRL, not sure who this fall to.

[taroface]

I can take this.

[taroface]

Closed by #10273.