Improve Open Graph content for referral URLs

In order to improve the conversion of referral links, we should optimize the contents of the Open Graph tags on URLs that contain referral tags.

When copying a referral URL from the [Settings > Referrals screen](https://www.minds.com/settings/other/referrals), the app appends a referrer parameter to the URL for the minds.com/register page.

`https://www.minds.com/register?referrer=mellamomrs`

We should optimize the OG tags for this URL when the referrer param is present.

![image](/uploads/dfa9b1bce873c98d0ae022c0f2051e03/image.png)

## Improved Open Graph spec

The basic gist is pulling in the name and avatar of the user who's username is in the referrer parameter. If the referrer parameter is blank or references a username that doesn't exist, OG tags can fall back to the default

| State    | URL                                                | og:url                                             | og:type | og:title                                 | og:image                                                         | og:description                                                                                                                                                            | og:site_name | rel canonical                  |
|----------|----------------------------------------------------|----------------------------------------------------|---------|------------------------------------------|------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------|--------------------------------|
| Current  | https://www.minds.com/register?referrer=mellamomrs | https://www.minds.com/register?referrer=mellamomrs | website | Register                                 | https://www.minds.com/static/en/assets/og-images/register-v3.png | Create a channel on Minds                                                                                                                                                 | Minds        | [none]                         |
| Improved | https://www.minds.com/register                     | https://www.minds.com/register                     | website | Join Minds, and Elevate the Conversation | https://www.minds.com/static/en/assets/og-images/default-v3.png  | Minds is an open source social network dedicated to Internet freedom. Speak freely, protect your privacy, earn crypto rewards and take back control of your social media. | Minds        | https://www.minds.com/register |
| Improved | https://www.minds.com/register?referrer=mellamomrs | https://www.minds.com/register?referrer=mellamomrs | website | Join Ryan on Minds                       | https://cdn.minds.com/icon/1271629611221913617/large/1643651274  | Minds is an open source social network dedicated to Internet freedom. Speak freely, protect your privacy, earn crypto rewards and take back control of your social media. | Minds        | https://www.minds.com/register |

## Acceptance

- [ ] When a user shares a link to the register page with the `referrer` param, then the Open Graph title and image reflect the user who's username is referenced.
- [ ] When a user shares a link to the register page without a valid username in the `referrer` param, then the Open graph title and image reflect the generic values described above.
- [ ] The `<rel canonical` tag on the page always points to `https://www.minds.com/register` (without params)

Story points: 1.0