Move SkParagraph bits into skparagraph directory.

This makes it more obvious that these files really are part of
SkParagraph and integrate with the Skia test framework and are not part
of core Skia. This is more like how Skottie is setup and helps prevent
misunderstandings about where additional files like this should go and
how the build should be structured.

Change-Id: Iaac060c97cffd2b0c29833c7b0403521d91bdb6a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/292439
Reviewed-by: Julia Lavrova <jlavrova@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>

modules/skparagraph/BUILD.gn

@@ -56,7 +56,7 @@ if (skia_enable_skparagraph) {
     source_set("tests") {
       if (skia_use_icu && skia_use_harfbuzz && paragraph_tests_enabled) {
         testonly = true
-        sources = [ "//tests/SkParagraphTest.cpp" ]
+        sources = [ "tests/SkParagraphTest.cpp" ]
         deps = [
           ":skparagraph",
           "../..:gpu_tool_utils",
@@ -70,7 +70,7 @@ if (skia_enable_skparagraph) {
     source_set("bench") {
       if (skia_use_icu && skia_use_harfbuzz && paragraph_bench_enabled) {
         testonly = true
-        sources = [ "//bench/ParagraphBench.cpp" ]
+        sources = [ "bench/ParagraphBench.cpp" ]
         deps = [
           ":skparagraph",
           "../..:skia",
@@ -83,7 +83,7 @@ if (skia_enable_skparagraph) {
     source_set("samples") {
       if (skia_use_icu && skia_use_harfbuzz) {
         testonly = true
-        sources = [ "//samplecode/SampleParagraph.cpp" ]
+        sources = [ "samples/SampleParagraph.cpp" ]
         deps = [
           ":skparagraph",
           ":utils",