fix(ngResource): don't convert literal values into Resource objects when isArray is true

Previously non-object literals would be thrown out of Resource responses with isArray===true, or
otherwise converted into Objects (in the case of string literals). The reason for this is because
shallowClearAndCopy iterates over keys, and copies keys into the destination. Iterating over String
keys results in integer keys, with a single-character value.

Not converting non-objects to Resources means that you lose the ability to perform Resource operations
on them. However, they become usable as strings, numbers, or booleans, which is important.

In the future, it would be useful to make these useful as Resources while still retaining their primitive
value usefulness.

Closes #6314
Closes #7741