fix: loading config from file reworked

Description

It turned out, that database names are being read from config file wrongly when database name ends with s.
Loading configuration has been reworked on Golang and the format of the config file has been changed a little bit.
Now not available otpions differs from CLI options in config file.

So correct config is:

- project: proj
  hostname: db1.vpn.io
  port: 5432
  dbname: dbname
  username: dbuser
  statement-timeout: 15
  epoch: 1
  html: true
  pdf: true

instead of

- config:
  hostname: db1.vpn.io
  port: 5432
  ...

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes and they have been reviewed OR there are no API changes

Related issue

#463 (closed)

Examples

Closes #463 (closed)