Update CODEOWNERS: reformatting, add lennartkats-db to specific areas (#3647)

## Changes

This updates the CODEOWNERS file:
* [change] I added myself for the templating code and the `bundle.go`
command group.
* [formatting] All lines have indentation-based alignment for
readability.
* [formatting] The core reviewer group for `*` is alphabetized for
readability.

Author: lennartkats-db

.github/CODEOWNERS

@@ -1,4 +1,6 @@
-* @pietern @andrewnester @shreyas-goenka @denik @anton-107
-cmd/labs @alexott @nfx
-cmd/pipelines @kanterov @lennartkats-db @jefferycheng1
-acceptance/pipelines @kanterov @lennartkats-db @jefferycheng1
+*                         @andrewnester @anton-107 @denik @pietern @shreyas-goenka
+/cmd/bundle/bundle.go     @andrewnester @anton-107 @denik @pietern @shreyas-goenka @lennartkats-db
+/libs/template/           @andrewnester @anton-107 @denik @pietern @shreyas-goenka @lennartkats-db
+/acceptance/pipelines/    @jefferycheng1 @kanterov @lennartkats-db
+/cmd/pipelines/           @jefferycheng1 @kanterov @lennartkats-db
+/cmd/labs/                @alexott @nfx