Refactor to use string IDs for executables #262

This commit unifies the concepts of executables having same ID
structure. It paves the way for more complex ID structure and using IDs
in collection files as part of new ID solution (#262). Using string IDs
also leads to more expressive test code.

This commit also refactors the rest of the code to adopt to the changes.

This commit:

- Separate concerns from entities for data access (in repositories) and
  executables. Executables use `Identifiable` meanwhile repositories use
  `RepositoryEntity`.
- Refactor unnecessary generic parameters for enttities and ids,
  enforcing string gtype everwyhere.
- Changes numeric IDs to string IDs for categories to unify the
  retrieval and construction for executables, using pseudo-ids (their
  names) just like scripts.
- Remove `BaseEntity` for simplicity.
- Simplify usage and construction of executable objects.
  Move factories responsible for creation of category/scripts to domain
  layer. Do not longer export `CollectionCategorY` and
  `CollectionScript`.
- Use named typed for string IDs for better differentation of different
  ID contexts in code.

tests/integration/presentation/components/Scripts/View/Tree/NodeContent/Markdown/CompositeMarkdownRenderer.spec.ts

@@ -225,7 +225,7 @@ function collectAllDocumentedExecutables(): DocumentedExecutable[] {
   ]);
   const allDocumentedExecutables = allExecutables.filter((e) => e.docs.length > 0);
   return allDocumentedExecutables.map((executable): DocumentedExecutable => ({
-    executableLabel: `${executable.name} (${executable.id})`,
+    executableLabel: `${executable.name} (${executable.executableId})`,
     docs: executable.docs.join('\n'),
   }));
 }