Fix invalid itemData references of 57 highlighting files

Summary:
Many highlightig files reference with attribute="xzy" non-existing
itemDatas. This was found by extending the highlighting indexer and
collecting all attribute values and compare these with the itemDatas.

The total number of broken files is 62.
This patch fixes 57 of these 62 files.

Remaining files with issues:
haml.xml.....: non-existing itemDatas: "Escaped Text", "Ruby embedded in haml", "Array"
julia.xml....: non-existing itemDatas: "String Char"
lilypond.xml.: non-existing itemDatas: "Tremolo"
metafont.xml.: non-existing itemDatas: "Verbatim", "Tex", "Bullet"
ocaml.xml....: non-existing itemDatas: "Ocamldoc Identifier"
prolog.xml...: non-existing itemDatas: "'quo Ted'"
relaxng.xml..: non-existing itemDatas: "Entity Reference"
rhtml.xml....: non-existing itemDatas: "RUBY RAILS ERB Text"
rmarkdown.xml: non-existing itemDatas: "Markdown", "Document Headers"
stata.xml....: non-existing itemDatas: "String2"
toml.xml.....: non-existing item...