chore(CODEOWNERS): Use usernames instead of groups

Use usernames instead of groups in the CODEOWNERS file to make the code
owners more transparent to external contributors.

This also solves the issue that when a team members picks up a review,
it is indivudally assigned as a reviewer of the PR, and all other team
members are removed from the reviewers list.

While at it, remove some entries which have become redundant because new
members were added to the kotlin-devs team in the meantime, and remove
the entry for SW360 because the code has not been touched in a while.

Signed-off-by: Martin Nonnenmacher <[email protected]>

Author: mnonnenmacher

.github/CODEOWNERS

@@ -2,11 +2,17 @@
 # last matching pattern is used, see
 # https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/creating-a-repository-on-github/about-code-owners#codeowners-syntax
 
-* @oss-review-toolkit/kotlin-devs
-*.md @oss-review-toolkit/core-devs
-/**/*Sw360* @oss-review-toolkit/kotlin-devs @bs-ondem @oheger-bosch
-/advisor/ @oss-review-toolkit/kotlin-devs @MarcelBochtler @oheger-bosch
-/clients/fossid-webapp/ @oss-review-toolkit/kotlin-devs @nnobelis
+# Members of @oss-review-toolkit/kotlin-devs.
+* @fviernau @MarcelBochtler @mnonnenmacher @nnobelis @oheger-bosch @sschuberth
+
+# Members of @oss-review-toolkit/core-devs.
+*.md @fviernau @MarcelBochtler @mnonnenmacher @sschuberth @tsteenbe
+
+# Owners of the web app reporter.
 /plugins/reporters/web-app-template/ @tsteenbe
-/spdx-utils/src/main/ @oss-review-toolkit/core-devs
-/LICENSE @oss-review-toolkit/core-devs
+
+# Members of @oss-review-toolkit/core-devs.
+/spdx-utils/src/main/ @fviernau @MarcelBochtler @mnonnenmacher @sschuberth @tsteenbe
+
+# Members of @oss-review-toolkit/core-devs.
+/LICENSE @fviernau @MarcelBochtler @mnonnenmacher @sschuberth @tsteenbe