operations-ui-manager: Use header capitalization™ in some strings
Use header capitalization in some strings from the file conflict dialog, such as "Replace with", "Merge with", "Original file" and "File conflict" and "File and Folder conflict". This change conforms with the HIG guidelines[1].
[1] https://developer.gnome.org/hig/guidelines/writing-style.html#header-capitalization
Closes #3373 (closed)
Edited by Automeris naranja