Part of #1241
### Changes
- Renames all instances of "Browsertrix Cloud" to "Browsertrix" on the
front end, emails, and documentation
---------
Co-authored-by: emma <hi@emma.cafe>
- Emails are now processed from Jinja2 templates found in
`charts/email-templates`, to support easier updates via helm chart in
the future.
- The available templates are: `invite`, `password_reset`, `validate` and
`failed_bg_job`.
- Each template can be text only or also include HTML. The format of the
template is:
```
subject
~~~
<html content>
~~~
text
```
- A new `support_email` field is also added to the email block in
values.yaml
Invite Template:
- Currently, only the invite template includes an HTML version, other
templates are text only.
- The same template is used for new and existing users, with slightly
different text if adding user to an existing org.
- If user is invited by the superadmin, the invited by field is not
included, otherwise it also includes 'You have been invited by X to join Y'
