LDAP admin settings design improvements

@nextcloud/ldap something for you! :) Quick tips on how to improve the LDAP app interface:

• The ui-… classes from the buttons override Nextcloud styles and should be removed :)

• The <span class="ui-button-text">…</span> element around the text is unnecessary and can be removed too (the "Detect Port" button is standard style and clearly looks like a button)

• The "Configuration OK" element can be moved to be left-aligned

• Same with the "Continue" and help elements, it can go below that and left-aligned. At the moment it’s floating weirdly in space.