Feature/add synth options call session

[Catharsis68]

@xquanluu this PR is based on PR #590

• Add speechSynthesisOptions from config verb to a Call Session
• In say task: if defined, apply the speechSynthesisOptions to this.options - but let them get overwritten by say.synthesizer.options

[davehorton]

@xquanluu do you have an opinion on this PR?

[xquanluu]

For me I don't know the issue related to this, but from the code, he wants to override say verb synthesizer options from config verb if say verb syntheizer.options is missing

[Catharsis68]

@xquanluu there is another PR #590 (which is not working) - the general issue was
"the config provides session-level settings, but if a verb specifies something different, that should take preference for that verb"

So a say node with synthesizer options should overwrite the general config.

This PR adds the synthesizerOptions to the call-session object in the config task. Otherwise it is never possible to access these options