"tools/changelog-helper.sh group-entries" grouping improvement suggestions

[pljones]

What is the current behaviour and why should it be changed?

The current sorting method means "Client:" and "Client/Server:" tagged entries can be mixed:

+- Client: Added "delete server" button to connect dialog (#3159).
+  (contributed by @pljones)
+
+- Client/Server: Display Qt versions for both build and runtime (#3231).
+  (contributed by @softins)
+
+- Client: Added "Delete Entry" button to Advanced Settings, Custom Directories (#3260).
+  (contributed by @AdamGLIN)

Ideally the grouping would keep all "Client:" entries together, all "Client/Server:" entries together (following "Client:") and all "Server:" entries together (following any "Client/Server:" entries).

Currently, each PR for Weblate gets a separate entry. Grouping should merge "Translations updated from Hosted Weblate" by "@weblate" into a single entry listing all the PR numbers

Currently, "Build:" entry sorting isn't done and grouping could be improved. For example:

+- Build: Updated bundled Qt6 to version 6.6.0 (#3182).
+  (contributed by @app/github-actions)
+
+- Build: Ensure apt version >=2.4 to prove that the system is Debian based (using apt and dpkg) and can validate the repo (#3199).
+  (contributed by @houbsta)
+
+- Build: Updated bundled Qt6 to version 6.6.1 (#3204).
+  (contributed by @app/github-actions)

It would be nice if there was a single "Build: Updated bundled Qt6" entry with "- versions 6.6.0, 6.6.1, 6.6.3" by "@app/github-actions".

Sorting and grouping all the "@app/github-actions" and "@app/dependabot" updates together like this would condense the change log significantly (reducing manual editing).