Introduce interleaved package and transitive target loading

Adds SkyFunctions and assorted values that implement interleaved
loading of packages and their targets' transitive dependencies.

They are not hooked up to any graph loading components, yet.

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MOS_MIGRATED_REVID=97278368
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyFunctions.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyFunctions.java
index 047db51..b6944c5 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyFunctions.java
@@ -42,6 +42,10 @@
   public static final SkyFunctionName TARGET_PATTERN = SkyFunctionName.create("TARGET_PATTERN");
   public static final SkyFunctionName PREPARE_DEPS_OF_PATTERNS =
       SkyFunctionName.create("PREPARE_DEPS_OF_PATTERNS");
+  public static final SkyFunctionName PREPARE_DEPS_OF_PATTERN =
+      SkyFunctionName.create("PREPARE_DEPS_OF_PATTERN");
+  public static final SkyFunctionName PREPARE_DEPS_OF_TARGETS_UNDER_DIRECTORY =
+      SkyFunctionName.create("PREPARE_DEPS_OF_TARGETS_UNDER_DIRECTORY");
   public static final SkyFunctionName RECURSIVE_PKG = SkyFunctionName.create("RECURSIVE_PKG");
   public static final SkyFunctionName TRANSITIVE_TARGET =
       SkyFunctionName.create("TRANSITIVE_TARGET");