Improve error message in `announce` response

[josecelano]

When tracker clients send a bad request, they get an encoded response like this:

Example request: https://tracker.torrust-demo.com/announce

Response:

d14:failure reason149:Cannot parse query params for announce request: missing query params for announce request in src/servers/http/v1/extractors/announce_request.rs:75:23e

Some people might think it's a bug in the tracker. I would change the error message from:

Cannot parse query params for announce request: missing query params for announce request in src/servers/http/v1/extractors/announce_request.rs:75:23

to:

Bad request. Cannot parse query params for announce request: missing query params for announce request in src/servers/http/v1/extractors/announce_request.rs:75:23

We cannot change the dict field name failure reason because it's defined in the BEPs

• https://www.bittorrent.org/beps/bep_0003.html
• https://www.bittorrent.org/beps/bep_0052.html