refactor: migrate changelogs to changesets format

refactor: add changesets
refactor: chose packages to publish

.changeset/tidy-buses-reflect.md

@@ -0,0 +1,9 @@
+---
+'@openstapps/core-tools': major
+'@openstapps/easy-ast': major
+---
+
+Migrate easy-ast to separate package
+
+The `easy-ast` part of `core-tools` has been moved to its own package.
+For migration, simply use the new package.