implement inlabel search keyword
Can specify only text which searches labels_all, or
specify languages. The language is parsed as follows:
- Spec is approximately (brackets indicate optional): term[@lang[,lang...]]
- Multiple languages are separated by commas
- If query is for a single language named the empty string or '*' query labels_all
- The fallbacks associated with the language can be added by appending * to the language name. Fallbacks without en can be added by appending +
- Languages, particularly those added by fallbacks, can be removed by prefixing the language with -. This also works with the + and * suffix.
- See test cases for other examples
Bug: T215967
Depends-On: Ib0ab9069c7e63640edb6f9c315dd20d9ecd94160
Change-Id: I8869fca7df3e1e1ef3bbcf74d5d6f4283688a6e1