The threee tags `<name>`, `</name>` and `<command>` were frequently used
with a leading space that this removes. The reason this habbit is so
widespread in testcases is probably that they have been copy and pasted.
Hence, fixing them all now might curb this practice from now on.
Closes#12028
- file://host.name/path/file.txt is a valid UNC path
\\host.name\path\files.txt to a non-local file transformed into URI
(RFC 8089 Appendix E.3)
- UNC paths on other OSs must be smb: URLs
Closes#7366
