ci: Add Action to check for tabs in JSON files

[GeckoEidechse]

Checks for tabs in all JSON files and fails if it finds any

 

Tabs vs Spaces

Before anyone complains why only spaces in JSON files instead of tabs for indentation:

• We already use spaces, this PR changes nothing
• It's way easier to check for tabs than spaces as you just need to check whether there's a \t as opposed having a parser that actually understands the JSON syntax.
• When doing suggestions during code review on GitHub, adding a tab is really annoying as pressing tab moves the cursor to the next element so instead you have to copy-paste a tab character from somewhere else

[Alystrasz]

Grep command looks fine, new CI job seems to be working according to run 20424196944.