refactor(models): refine data structure

[BioPhoton]

This PR includes:

• Replaced RunnerOutput schema object with AuditOutput array

// before
type RunnerOutput = {
  audits: AuditOutputSchema[]
}

// after
type AuditOutputsSchema

• Introduce reusable schema for date and duration
• Renamed name to title in plugin metadata to align with audit metadata
• Introduce reusable schema for meta information and use it in audit and plugin

// shared meta
type MetaInformation {
  slug: string,
  title: string,
  description?: string,
  docsUrl?: string
}

• Rename AuditMetadata to Audit
• Remove slug from metaSchema
• Add metaSchema to CategoryConfig
• Add metaSchema to AuditGroup
• Flatten PluginConfig#meta information into PluginConfig
• Remove label from all meat information
• Add meta info to AuditOutput
• Add meta info to PluginOutput
• Make report independent from config
  • Add categories to report
  • refactor report to MD
  • refactor report to stdout

closes #50

[matejchalk]

Nice improvement 👍