fix: route Files API by encoded path, url parameter in metadata response is URL encoded

[Maxim-Gadalov]

1. Core should urldecode path segments, not the full path (as https://github.com/epam/ai-dial-core/blob/development/src/main/java/com/epam/aidial/core/controller/ControllerSelector.java#L47C1-L47C1)
2. url in the metadata should be correct url. No extra encoding or decoding is required to access it.
3. name and parentPath in metadata a NOT parts on the url. They should be encoded when building url (as per URL RFC).
4. Symbol / is reserved as a path segments separator and not allowed in file names and directory names. Requests with / in a file name or directory name will be 400 Bad request. Following requests will end up with 400:
   PUT v1/files/a/b/c%2Fd
   GET v1/files/a/b/c%2Fd
   GET v1/files/metadata/a/b/c%2Fd