revise JavadocIndexer to get interface element

[ebarboni]

Hi, this allow all-classes.xml to have all the interface + enum. I could not make a nice regexp. I rewrite the parsing using simple jsoup by using the one of ide/libs.flexmark/external

This should fix the search issue @errael find.

[mbien]

build fails atm since it can't find jsoup in cp

[ebarboni]

getting lib from ide clusters is too deep, trying to put in in the nbbuild/external

[ebarboni]

it's now green

[ebarboni]

done via #4969