only rewrite ui-config when there is change

[w-e-w]

• only rewrite ui-config on load when there is change

ui-config.json is is always rewritten on webui load, even when there's no change
there's no point and can cause file corruption if webui is killed at a inappropriate time during load

and yes I was unlucky enough that this actually happened to me

Changes

• create a copy of the dictionary read from file and compare before writing if there is no change then don't write the file
• a minor typo fix

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests