Add environment variable error handling

[MartinMinkov]

Description

This PR introduces improved error handling for environment variables and better compatibility checks for the Postgres schema. The changes include:

1. Checking the Postgres schema compatibility with the tables the server uses on startup.
2. Adding a new environment variable, ENABLE_LOGGING, allows users to specify if they want any logging. If logging is enabled, it will direct to stdout first. If JAEGER_LOGGING is enabled, the environment variables related to that functionality will also be checked.
3. Adding POST to the allowed CORS methods to support GraphQL.
4. Minor refactors to improve code quality and maintainability.

Addresses #4 #18

Impact:

These changes will improve the reliability and stability of the server. The improved error handling for environment variables will catch potential issues early on and prevent the server from starting with incorrect configurations. The added compatibility check for the Postgres schema will ensure that the server uses the correct tables, improving data accuracy and consistency. Adding the ENABLE_LOGGING environment variable will give users more control over logging and provide better visibility into the server's operation. Adding POST to the allowed CORS methods will support GraphQL and improve the user experience. The minor refactor will improve the maintainability of the code and make future development easier.

[shimkiv]

• Overall LGTM but left some comments.

[shimkiv]

Also it seems that DB connection string and schema validity is checked for the first host in multi-host connection string provided.

[MartinMinkov]

Also it seems that DB connection string and schema validity is checked for the first host in multi-host connection string provided.

Multi-host checking seems to be more complicated; I will address this in another PR. #29

[shimkiv]

• LGTM, left another comment but approved.
• Thank you.