fix: change imports and refactor the project structure to be able compiling pghrep (#505)

Description

Change imports and refactor the project structure to be able compiling pghrep :

• init Go modules, update required Go version to 1.17
• refactor imports, remove local paths of packages
• refactor the project structure: create a single point of running, get rid of the src directory
• adjust Makefile and Dockerfile according to the structure: remove unnecessary commands

Related issue

#505 (closed)

Examples

Checklist

• 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

Closes #505 (closed)