Enforce casing in operations and entities (#1818)

* Enforce casing in operations and entities

* Fix small error and remove improts

* Fix formatting

* Add fullstop to error messages

* Add naming changes to changelog and migration guide

* Update waspc/ChangeLog.md

* Update web/docs/migrate-from-0-11-to-0-12.md

* fix

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Co-authored-by: Martin Šošić <[email protected]>
Co-authored-by: Martin Sosic <[email protected]>