refactor: update dependencies and fix resulting errors

Upgraded JSON Schema from version 6 to version 7
Upgraded TypeDoc version to latest
Replaced 'jsonschema' with 'json-schema' package to better comply with 'ts-json-schema-generator'
Replace JSON Schema validation with AJV in areas where it wasn't used previously
Removed commander help output as it causes strange issues

test/schema.spec.ts

@@ -33,7 +33,8 @@ export class SchemaSpec {
 
     const schema = converter.getSchema('Foo', '0.0.1');
     expect(schema).to.be.deep.equal({
-      $schema: 'http://json-schema.org/draft-06/schema#',
+      $id: 'https://core.stapps.tu-berlin.de/v0.0.1/lib/schema/Foo.json',
+      $schema: 'http://json-schema.org/draft-07/schema#',
       additionalProperties: false,
       definitions: {
         FooType: {
@@ -67,7 +68,6 @@ export class SchemaSpec {
         },
       },
       description: 'This is a simple interface declaration for\ntesting the schema generation and validation.',
-      id: 'https://core.stapps.tu-berlin.de/v0.0.1/lib/schema/Foo.json',
       properties: {
         lorem: {
           description: 'Dummy parameter',