The following commit completes legal information of Organizations to comply with the optional properties of an Imprint. Following properties have been added:

• companyRegistration with the range Certification
• legalAddress with the range PostalAddress
• legalRepresentative with the range Person.

Closes: #4366

Background regarding the legal information required on company run websites in Europe

Germany, Austria and other jurisdiction require companies (organizations) to publish all legal information of a company on their website. Also Google does that for example here:
Google Germany Imprint

In fact for example to be eligible to run Google Ads you are required to ad the information to your own website.

It is advised by many search engines to use this page (or any other about us page) to contain the structured data about the website publishing organization. Facebook for example also allows to add the information to pages:
Add an Impressum to your Facebook Page

We seemingly have everything in there inside organization, but not the basic legal fields that are even required by Google to do certain things.

Fixes: #4366

Addition of new properties to Organization

To allow standardisation of the information set I have tried with this PR to align the organization structured data with the legal requirements of the imprint by allowing more values.

• legalRepresentative (Person): the legal representative of a company such as CEO or managing director.
• company registration (certification): the company registry number and the issuer of the number.

Upon close inspection following values are not mandatory but can be contained in the Imprint:

• Common Stock Capital of your LLC or unlisted company (eg. 10.000 EUR of which 2.500 EUR Paid up);
  legal representative

Example Implementation

The example below contains also a proposal for stock capital, if desired.

{
  "@context": "https://schema.org",
  "@type": "Organization",
  "url": "https://www.google.com",
  "sameAs": [
    "https://example.net/profile/example1234",
    "https://example.org/example1234"
  ],
  "logo": "https://www.google.com/images/logo.png",
  "name": "Google",
  "legalName": "Alphabet LLC",
  "legalRepresentative": {
    "@type": "Person",
    "name": "Larry Page"
  },
  "hasCompanyRegistration": {
    "@type": "Certification",
    "issuedBy": {
      "@type": "Organization",
      "name": "Chamber of Commerce of Wondertown"
    },
    "name": "Company Registration",
    "certificationIdentification": "WT-123456"
  },
  "description": "The example corporation is well-known for producing high-quality widgets",
  "email": "[email protected]",
  "telephone": "+47-99-999-9999",
  "address": {
    "@type": "PostalAddress",
    "streetAddress": "Rue Improbable 99",
    "addressLocality": "Paris",
    "addressCountry": "FR",
    "addressRegion": "Ile-de-France",
    "postalCode": "75001"
  },
  "legalAddress": {
    "@type": "PostalAddress",
    "streetAddress": "Rue Improbable 99",
    "addressLocality": "Paris",
    "addressCountry": "FR",
    "addressRegion": "Ile-de-France",
    "postalCode": "75001"
  },
  "vatID": "FR12345678901",
  "iso6523Code": "0199:724500PMK2A2M1SQQ228"
}