Rename go files that contain "main" function to main.go.

This is a good Go convention that we should follow.

PiperOrigin-RevId: 378538679

test/cmd/test_app/BUILD

@@ -7,7 +7,7 @@ go_binary(
     testonly = 1,
     srcs = [
         "fds.go",
-        "test_app.go",
+        "main.go",
     ],
     pure = True,
     visibility = ["//runsc/container:__pkg__"],

test/runner/BUILD

@@ -5,7 +5,7 @@ package(licenses = ["notice"])
 go_binary(
     name = "runner",
     testonly = 1,
-    srcs = ["runner.go"],
+    srcs = ["main.go"],
     data = [
         "//runsc",
     ],

tools/go_generics/BUILD

@@ -5,8 +5,8 @@ package(licenses = ["notice"])
 go_binary(
     name = "go_generics",
     srcs = [
-        "generics.go",
         "imports.go",
+        "main.go",
         "remove.go",
     ],
     visibility = ["//:sandbox"],