Rename encoders to Sk*ImageEncoder

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1836493002
CQ_EXTRA_TRYBOTS=client.skia.compile:Build-Ubuntu-GCC-x86_64-Release-CMake-Trybot,Build-Mac-Clang-x86_64-Release-CMake-Trybot

Review URL: https://codereview.chromium.org/1836493002
diff --git a/public.bzl b/public.bzl
index 65d5e03..ba10d31 100644
--- a/public.bzl
+++ b/public.bzl
@@ -165,6 +165,7 @@
         "src/ports/SkFontMgr_fontconfig.cpp",
         "src/ports/SkFontMgr_fontconfig_factory.cpp",
         "src/ports/SkImageDecoder_empty.cpp",
+        "src/ports/SkImageEncoder_none.cpp",
         "src/ports/SkImageGenerator_none.cpp",
         "src/ports/SkTLS_none.cpp",
     ],
@@ -212,6 +213,7 @@
         "src/ports/SkFontMgr_custom_empty_factory.cpp",
         "src/ports/SkFontMgr_empty_factory.cpp",
         "src/ports/SkImageDecoder_empty.cpp",
+        "src/ports/SkImageEncoder_none.cpp",
         "src/ports/SkImageGenerator_none.cpp",
         "src/ports/SkTLS_none.cpp",
     ],
@@ -267,6 +269,7 @@
         "src/ports/SkFontMgr_custom_embedded_factory.cpp",
         "src/ports/SkFontMgr_custom_empty_factory.cpp",
         "src/ports/SkFontMgr_empty_factory.cpp",
+        "src/ports/SkImageDecoder_empty.cpp",
         "src/ports/SkImageGenerator_none.cpp",
         "src/ports/SkTLS_none.cpp",
     ],
@@ -396,14 +399,6 @@
         "tools/ProcStats.h",
         "tools/Resources.cpp",
         "tools/Resources.h",
-        "tools/SkBitmapRegionCanvas.cpp",
-        "tools/SkBitmapRegionCanvas.h",
-        "tools/SkBitmapRegionCodec.cpp",
-        "tools/SkBitmapRegionCodec.h",
-        "tools/SkBitmapRegionDecoder.cpp",
-        "tools/SkBitmapRegionDecoder.h",
-        "tools/SkBitmapRegionSampler.cpp",
-        "tools/SkBitmapRegionSampler.h",
         "tools/flags/*.cpp",
         "tools/flags/*.h",
         "tools/random_parse_path.cpp",