[Feedback requested] Remove `webMail` element from configs

We want to clean up the config files to only include elements that Thunderbird supports. One element that Thunderbird is very unlikely to ever use is webMail. So we'd like to remove it.

But we don't want to break software relying on this information. If you are the author of such a software, please let us know in a comment, so we can work out a removal date that allows you to migrate to a different database or mechanism.

Example of a webMail element:

<webMail>
  <loginPage url="https://accounts.google.com/ServiceLogin?service=mail&amp;continue=http://mail.google.com/mail/" />
  <loginPageInfo
    url="https://accounts.google.com/ServiceLogin?service=mail&amp;continue=http://mail.google.com/mail/">
    <username>%EMAILADDRESS%</username>
    <usernameField id="Email" />
    <passwordField id="Passwd" />
    <loginButton id="signIn" />
  </loginPageInfo>
</webMail>

Start by locating the ISPDB configuration files containing the element and review the existing comment for affected consumers. Confirm whether any software still relies on these entries before removing them, and define completion as removing the element without breaking a documented migration path.