[CB-7417][File tests] added proper matcher to compare fullPath property

Specs : 111, 112 & 121-124, were using [toBe, toEqual] to compare a
fullPath property from an Entry.
The right matcher to use is toCanonicallyMatch, that it makes a fair and
right comparison across platforms.

In addition, special case to compare Windows Phone entries, was removed.
[CB-7418][DirectoryEntry] Added fullPath variable as part of condition

As well as NativeURL property, the fullPath variable should be part of
the condition to avoid that a null value becomes a path, by adding a
slash at the end of the undefined string.
So in order to add a slash to it, fullPath should contain a value.
Merge branch 'CB-7418' of https://github.com/martincgg/cordova-plugin-file