Add Manuel as an emeritus lead maintainer, add myself as the new lead

Manuel has been unresponsive on the PR and the post on Discourse, but
he had previously stepped down as a component maintainer in Clang due
to a lack of bandwidth, so I think it's safe to move him to the
inactive list.

If he wants to be lead again, I'll happily pass the duties back to him.

Author: AaronBallman

clang-tools-extra/Maintainers.txt

@@ -14,8 +14,8 @@ assistance.
 
 Lead Maintainer
 ---------------
-| Manuel Klimek
-| klimek@google.com (email), r4nt (GitHub)
+| Aaron Ballman
+| aaron@aaronballman.com (email), aaron.ballman (Phabricator), AaronBallman (GitHub), AaronBallman (Discourse), aaronballman (Discord), AaronBallman (IRC)
 
 
 clang-tidy
@@ -60,6 +60,11 @@ The following people have graciously spent time performing maintainership
 responsibilities but are no longer active in that role. Thank you for all your
 help with the success of the project!
 
+Emeritus Lead Maintainers
+-------------------------
+| Manuel Klimek ([email protected] (email), r4nt (GitHub))
+
+
 Inactive component maintainers
 ------------------------------
 | Nathan James ([email protected]) -- clang-tidy