The chunk encoding was hardcoded there because it mostly doesn't
matter what encoding is chosen in that test. Since type 1 is
battle-hardened enough, I'm switching to type 2 here so that we can
catch unexpected problems as a byproduct. My expectation is that the
chunk encoding doesn't matter anyway, as said, but then "unexpected
problems" contains the word "unexpected".
This adapts some functionality from the Go standard library for string
literal lexing and unquoting/unescaping.
The following string types are now supported:
Double- or single-quoted strings:
These support all escape sequences that Go supports in double-quoted
string literals. The difference is that Prometheus also has
single-quoted strings (instead of single-quoted runes in Go). Raw
newlines are not allowed.
Backtick-quoted raw strings:
Strings quoted in backticks are treated as raw strings just like in Go
and may contain raw newlines and other special characters directly.
Fixes https://github.com/prometheus/prometheus/issues/1122
Fixes https://github.com/prometheus/prometheus/issues/1121
