Migrate from ADODB to PDO

[Groruk]

Description

This PR will migrate all the SQL queries used in the web panel to PDO with prepared statements.

TODO

• Migrate last queries
• Refactor some of the code duplication
• Optimize some of the bigger queries (Suggestion regarding database structure #367)
• Test migrated queries
• Hotfix Steam Universe changing upon input (web panel) #568 (until Replace the Steam2 ID format with Steam Account ID #604 is implemented later)

Issues affected by this PR

#213
#214
#367
#568
#603
#606

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.