Add support of log consumer configuration properties for hierarchical prefixes customization

[YevgeniyShunevych]

Add support of log consumer configuration properties:

• MessageNestingLevelIndent
• MessageStartSectionPrefix
• MessageEndSectionPrefix

Usage

{
  "logConsumers": [
    {
      "type": "trace",
      "messageNestingLevelIndent": "- ",
      "messageStartSectionPrefix": "> ",
      "messageEndSectionPrefix": "< "
    }
  ]
}