Deprecate Parser implementation methods (will be private in next release)

Deprecate Parser implementation methods (will be private in next release)

The following public methods were renamed and made private; the old name
is hard-deprecated and calls the new renamed private method:

Parser::doMagicLinks() => handleMagicLinks()
Parser::doDoubleUnderscore() => handleMagicLinks()
Parser::doHeadings() => handleHeadings()
Parser::doAllQuotes() => handleAllQuotes()
Parser::replaceExternalLinks() => handleExternalLinks()
Parser::replaceInternalLinks() => handleInternalLinks()
Parser::replaceInternalLinks2() => handleInternalLinks2()
Parser::getVariableValue() => expandMagicVariable()
Parser::initialiseVariables() => initializeVariables()
Parser::formatHeadings() => finalizeHeadings()
Parser::test{Pst,Preprocess,Srvus}() => fuzzTest{Pst,Preprocess,Srvus}()

Additionally, the following methods are not used externally, but are
used outside the Parser class by core code.  They have been marked
@internal:

Parser::doQuotes() (used by {{#displaytitle}}),
Parser::getExternalLink{Rel,Attribs}() (used by Linker),
Parser::normalizeLinkUrl() (used by Special:LinkSearch and elsewhere).
Parser::{brace,arg,extension}Substitution() (used by PPFrame)

Code search query:
https://codesearch.wmflabs.org/deployed/?q=do%28MagicLinks%7CDoubleUnderscore%7CHeadings%7CAllQuotes%29%7Creplace%28ExternalLinks%7CInternalLinks%28%7C2%29%29%7CgetVariableValue%7CinitialiseVariables%7CformatHeadings%7Ctest%28Pst%7CPreprocess%7CSrvus%29%7CdoQuotes%7CgetExternalLink%28Rel%7CAttribs%29%7CnormalizeLinkUrl%7C%28brace%2Carg%2Cextension%29Substitution&i=nope&files=&repos=

Bug: T236810
Change-Id: I19a43ffc5dcfdd2981b51079c33422c964acb076