bp2build/queryview: codegen control sequences literally.

See b/184026959 for an instance where a genrule's cmd contains \n, and
the codegenerator generates an applied newline. It should be the
original newline control sequence literal.

Test: TH, bp2build unit test
Fixes: 184026959

Change-Id: Idb99ea87c75dfa4cb3ae679f98d8f61cb5a5ab09