[feat] Object storage of configuration

[lgrd]

Need

The entire configuration is on a file-system. But it could be useful to have it inside an object storage.

Functionnalities

• Have the choice between a file and an object storage. The choice is made for the entire configuration.
• Be able to read the configuration inside an object storage

Tasks

Before coding

• Choose an object storage
• Specify the new IO of the CLI (ROAD2_CONF_FILE will still exist but there will be new ones, like ROAD2_CONF_TYPE = 'file' or 'object')
• Find a solution for all 'directory' attributes inside the service.conf. All the other attributes are object compatible. There are files and directory for OSRM et Valhalla sources but it can't be different. It has to be files and directory locally.

Code it

• Code it. See next paragraph

After or during coding

• Update tests
  • utest/itest if modification of a classe
  • rtest if modification of an API
  • ctest if modification of a configuration
• Run tests
  • Inside the docker provided by the project : rtest, ctest, utest, itest
  • Manually if necessary
• Update the documentation
  • changelog.md
  • documentation directory

Code

• Create a reader using promises/readFile for file, and use it everywhere in the code
• Create getGlobalConfiguration() inside road2.js to handle the different parameters of the CLI. All parameters has to be read via nconf. They could be via -- or inside the ENV.
• To complete...