caddyhttp: fix escaped path matcher over-matching longer paths

[alhudz]

Repro: path /foo%2fbar (a %-escaped pattern with no trailing wildcard) matches a request to /foo%2fbarbaz. The plain pattern /foobar correctly does not match /foobarbaz, so escaped patterns silently behave like prefix matches.
Cause: matchPatternWithEscapeSequence walks the pattern and escaped path in lock-step and stops once the pattern is consumed, so trailing path bytes never make it into the string handed to path.Match; it then only ever sees the prefix.
Fix: append the remaining (normalised) path bytes after the loop so path.Match compares the whole path. Exact patterns now reject longer paths while wildcard patterns are unaffected.

[steadytao]

@alhudz the code is fine but we really need the assistance disclosure mate...