Move send of logs logic to mergin-client

[JanCaha]

Simplify sending the logs by moving the logic to mergin-client

Fixes #633

[JanCaha]

@ValentinBuira bigger part of the code was actually moved from plugin to the mergin-client, it is already merged there MerginMaps/python-api-client#243.

[RastoHu]

@JanCaha @tomasMizera
I tried to send diagnostic log to localhost and got this error in plugin:

ee server
plugin: Mergin b103511

[MarcelGeo]

Hey guys here. I found the issue here with sending POST request in a client. We are sending here "?" part of url encoded , then server could not find the whole url /v2/diagnostic-logs%3F ... as ? is part of url which is can not be encoded.

in method def post we need to handle query string properly (similar to def get). I think we need better testing of things which are going to py client / plugin by development.