Improve logging of apexd boot sequence

* Log apexes scanned by ApexFileRepository
* Remove log line from ScanApexFiles, since that function also uses
  ApexFileRepository
* Log processed compressed apexes

Test: adb logcat
Change-Id: I147b2ec81fbcf6704bdd6928f60b1ea38686b339

apexd/apex_file.cpp

diff --git a/apexd/apex_file.cpp b/apexd/apex_file.cpp
index 61e819d..89ff213 100644
--- a/apexd/apex_file.cpp
+++ b/apexd/apex_file.cpp
@@ -410,6 +410,8 @@
 Result<void> ApexFile::Decompress(const std::string& dest_path) const {
   const std::string& src_path = GetPath();
 
+  LOG(INFO) << "Decompressing" << src_path << " to " << dest_path;
+
   // We should decompress compressed APEX files only
   if (!IsCompressed()) {
     return ErrnoError() << "Cannot decompress an uncompressed APEX";