[Import-code-cleanup] Mark a few functions deprecated for clarity & mark parser class internal

[eileenmcnaughton]

Overview

Mark a few functions deprecated for clarity & mark parser class internal

Before

There was a suggestion that extensions might be using some of these functions - it's not supported as they are not a supported / defined interface, but it seems adding deprecated would make that clearer

After

Marked deprecated, class marked internal

Technical Details

I do think it is reasonable to develop a supported interface for imports - but one has not been defined as yet

Comments

[civibot]

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