normalize: replacement_dict should be ReplacementDict instance

Passing ReplacementDict instances into CommandLinker ensures that RD
instance methods are available there.

refs #6911
transcoder: use existing replacement_dict methods

Previously, transcoder was using its own implementations of a few of
the ReplacementDict methods. Instead, accept the ReplacementDict
instance passed in from the normalize client script and call its
methods.

refs #6911
dicts tests: SIP is usually assigned even for file-only