uri: speedup encode and decode functions

Patch replaces encoding and decoding functions written in Lua with
functions implemented in C.

Performance of Lua implementation (before the patch):

```
uri.escape   152.37  runs/sec
uri.unescape 263.44  runs/sec
```

Performance of C implementation (after the patch):

```
uri.escape   4983.03  runs/sec
uri.unescape 4197.19  runs/sec
```

Follows up #3682

NO_CHANGELOG=see previous commit
NO_DOC=see previous commit

Co-authored-by: Alexander Turenko <alexander.turenko@tarantool.org>