Support "Want-Review: all" footer

Bug: b/376705702
Change-Id: Iaf2a2fc719a3a14c895a1ba9333fe041f47b37c6
Reviewed-on: https://bluetooth-review.googlesource.com/c/All-Projects/+/2220
Reviewed-by: Danielle Kay <danikay@google.com>

project.config

diff --git a/project.config b/project.config
index 68e48d4..a4d2463 100644
--- a/project.config
+++ b/project.config
@@ -108,3 +108,7 @@
 	applicableIf = -topic:\"\"
 	submittableIf = is:false
 	canOverrideInChildProjects = false
+[submit-requirement "Want-Review-From-All"]
+	description = A 'Code-Review' vote is required from all reviewers.
+	applicableIf = footer:\"Want-Review: all\" -label:Code-Review>=1,users=human_reviewers
+	submittableIf = label:Code-Review>=1,users=human_reviewers