urlapi: remove percent encoded dot sequences from the URL path

Treat %2e and %2E to be "dot equivalents" in the function and remove
such sequences as well, according to RFC 3986 section 5.2.4. That is
also what the browsers do.

This DOES NOT consider %2f sequences in the path to be actual slashes,
so there is not removal of dots for those.

This function does not decode nor encode any percent sequences.

Also switched the code to use dynbuf.

Extends test 1395 and 1560 to verify.

Fixes #16869
Closes #16870