Select current server URL when Server URL configuration dialog is launched

[lognaturel]

We see from error logs on the demo server that some users start typing their URL as a suffix to whatever URL is currently configured rather than clearing the field and changing its value. I think an easy improvement for now would be to select the text in that box so if a user just starts typing the text will be replaced. (Error log, needs auth)

• [ ] Given I'm on the server settings page And I have a server configured When I click on "URL" And immediately start typing https://example.com without clearing the field or tapping in it And click OK Then the configured server URL is https://example.com (instead of <previous-url>https://example.com)