java,runfiles: merge classes

This commit prepares simplifying the Java runfiles
library, which itself prepares mergint the
manifest-based and directory-based logic so that
the Runfiles class could handle both at the same
time.

This commit only moves classes around:
- moves the ManifestBased and DirectoryBased
  classes into Runfiles, as nested classes
- adds a createManifestBasedForTesting and
  createDirectoryBasedForTesting method to create
  the classes for testing
- moves the ManifestBasedTest and
  DirectoryBasedTest into RunfilesTest

Otherwise this commit has no functional change.

Change-Id: I56b582c1a95793b0a871748697673b53a780f0fb
PiperOrigin-RevId: 194227675

src/tools/runfiles/java/com/google/devtools/build/runfiles/BUILD

@@ -12,8 +12,6 @@ filegroup(
 filegroup(
     name = "java-srcs",
     srcs = [
-        "DirectoryBased.java",
-        "ManifestBased.java",
         "Runfiles.java",
         "Util.java",
     ],
@@ -40,18 +38,6 @@ java_test(
     deps = [":test_deps"],
 )
 
-java_test(
-    name = "DirectoryBasedTest",
-    srcs = ["DirectoryBasedTest.java"],
-    deps = [":test_deps"],
-)
-
-java_test(
-    name = "ManifestBasedTest",
-    srcs = ["ManifestBasedTest.java"],
-    deps = [":test_deps"],
-)
-
 java_test(
     name = "UtilTest",
     srcs = ["UtilTest.java"],

src/tools/runfiles/java/com/google/devtools/build/runfiles/BUILD.tools

@@ -3,8 +3,6 @@ package(default_visibility = ["//visibility:private"])
 filegroup(
     name = "java-srcs",
     srcs = [
-        "DirectoryBased.java",
-        "ManifestBased.java",
         "Runfiles.java",
         "Util.java",
     ],