[2.0] refactor component

[jkowalleck]

after

• Added first-class hardware support #982
• Refactored service into a component type #975

the current component should be split in

• baseComponent - core properties of a component
• serviceComponent - inherit from baseComponent and add service-specific properties and requirements
• softwareComponent - inherit from baseComponent and add {application,framework,library,...}-specific properties and requirements
• hardwareComponent - inherit from baseComponent and add service-specific properties and requirements
• fileComponent - inherit from baseComponent and add file-specific properties and requirements
• dataComponent - inherit from baseComponent and add data-specific properties and requirements
• ... and so on - for each component type

I would even put the baseComponent, serviceComponent, etc ... under /$defs/component/$defs/,
not under /$defs/

after that split, the current component becomes a oneOf ala

{
  "$defs": {
    "component" : {
      "oneOf": [
         {"$ref": "#$defs/component/$defs/serviceComponent"}
         {"$ref": "#$defs/component/$defs/hardwareComponent"},
         {"$ref": "#$defs/component/$defs/...Component"},
       ],

       "$defs": {
         "baseComponent": {
           "$comment": "This is a mixin. make sure to use `unevaluatedProperties` in the usage downstream"
           "type": "object",
           "required": [ ... ] 
           "properties": {
             "type": { "enum": ["service", "device", ...] }, 
             "bom-ref": ...,
             "parties": ...
             "group": ...,
             "name": ...,
             "description": ...,
             "version": ...,
             "versionRange": ..., 
             "isExternal": ..., 
             ...
             "components": { "$ref": "#$defs/components" }
           }
         },
         "serviceComponent": {
           "allOf": [{ "$ref": "#/$defs/component/$defs/baseComponent" }],
           "titile": "Service Component",
           "type": "object",
           "required": ["endpoint", ...]
           "properties": {
             "type": { "enum": ["service"] },
             // service-specific properties
             "endpoint": ...,
             "isExternal": { "default": true }, 
             ...
             "components": { "$comment": "make all items being required of a certain `type`" }
           },
           "unevaluatedProperties": false
         },
         "...Component": { ... },
       } 
    }
  }


}