Add core .clang-format and format all source

[tomduncalf]

What, How & Why?

Add consistent formatting to our C++ files using the same .clang-format as core

Applied to existing files using for i in `find src -name "*.?pp" | grep -v catch`; do echo $i; clang-format --style=file $i -i; done from the root directory

☑️ ToDos

• 📝 Changelog entry
• 📝 Compatibility label is updated or copied from previous entry
• 🚦 Tests
• 📱 Check the React Native/other sample apps work if necessary
• 📝 Public documentation PR created or is not necessary
• 💥 Breaking label has been applied or is not necessary

If this PR adds or changes public API's:

• typescript definitions file is updated
• jsdoc files updated
• Chrome debug API is updated if API is available on React Native