Fix bug in name escaping for PSUSensor

PSU sensor has a bug where if the name includes any invalid characters,
it crashes when attempting to launch.  This is a problem, and very much
not expected behavior.

The root cause of this is that PSU combine event is creating a dbus API
path from the object name, but neglects to escape it properly.

The previous method to escape this was inlined inside sensor.hpp, so
that has been promoted to a new utility function, escapeForDbus which
can return an escaped name string to use in paths.

Through the course of adding this to the sensors namespace and including
it, it turns out that "sensors" is overloaded, and including it causes
both compile time errors from the overloaded name, and link time errors
from the lack of "inline" on the utility methods.  This commit also as a
matter of cleanup moves everything in SensorPaths.hpp into an
alternative file, SensorPaths.cpp, and includes that file in sensor
utils.

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: Id9ed915e7e0e13ee7bded67a785ab0fa58982ca8
diff --git a/meson.build b/meson.build
index 3932a14..13d9d51 100644
--- a/meson.build
+++ b/meson.build
@@ -41,7 +41,7 @@
 
 utils_a = static_library(
     'utils_a',
-    'src/Utils.cpp',
+    ['src/Utils.cpp', 'src/SensorPaths.cpp'],
     implicit_include_directories: false,
     include_directories: 'include',
 )