Use maps in bazel *attribute types

This is to simplify the process of resolving label + exclude labels
across the various configuration axes we have and across the various
properties/modules that use this behavior.

Test: ci/bp2build.sh && ci/mixed_droid.sh
Change-Id: I8efae3e75ddb365384f5caaf5bb504a5206618d3
diff --git a/bp2build/build_conversion_test.go b/bp2build/build_conversion_test.go
index b1c342c..6d0a9b2 100644
--- a/bp2build/build_conversion_test.go
+++ b/bp2build/build_conversion_test.go
@@ -1109,8 +1109,8 @@
         "out",
     ],
     srcs = [
-        "in1",
         "srcs-from-3",
+        "in1",
     ],
 )`,
 			description: "genrule applies properties from genrule_defaults transitively",
@@ -1535,10 +1535,10 @@
 			expectedBazelTargets: []string{`filegroup(
     name = "fg_foo",
     srcs = [
-        "//dir:e.txt",
-        "//dir:f.txt",
         "a.txt",
         "b.txt",
+        "//dir:e.txt",
+        "//dir:f.txt",
     ],
 )`,
 			},
@@ -1575,9 +1575,9 @@
 			expectedBazelTargets: []string{`filegroup(
     name = "fg_foo",
     srcs = [
+        "a.txt",
         "//dir/subdir:e.txt",
         "//dir/subdir:f.txt",
-        "a.txt",
     ],
 )`,
 			},