std: rename zig.Configuration to Build.Configuration

BRANCH_TODO

@@ -1,4 +1,3 @@
-* rename std.zig.Configuration to std.Build.Configuration
 * replace union(@This().Tag)
 * replace b.dupe() with string internment
 * don't forget to add -listen arg back
@@ -10,3 +9,4 @@
 * get zig tests passing
 * test a bunch of third party projects / help people migrate
 * refactor with DefaultingEnum
+* add flag for compiling maker in debug mode

lib/std/Build.zig

@@ -22,7 +22,7 @@ pub const Step = @import("Build/Step.zig");
 pub const Module = @import("Build/Module.zig");
 pub const abi = @import("Build/abi.zig");
 /// The serialized output of configure phase ingested by make phase.
-pub const Configuration = @import("zig/Configuration.zig");
+pub const Configuration = @import("Build/Configuration.zig");
 
 /// Shared state among all Build instances.
 graph: *Graph,