[C++][sql][lua] Raise influence cap and reset weekly influence

[Nobutadas]

I affirm:

• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

• Makes it so influence points are additive instead of a shared cap.
• Resets the influence points to 0 for all 4 nations on the weekly tally.
• Sets a cap of 250,000 shared influence points that can be adjusted as a main.lua setting. It is believed that retail has this uncapped, but this is not completely verified. 250,000 will allow other nations to still participate in a region's conquest even if one nation pulls significantly ahead but still be a challenge, similar to what has been observed in retail. The code can currently support up to 20 million through the setting.
• Sets the conquest SQL to start the influence points of all regions at 0 for new servers; initial region control has been untouched.
• Fixes a bug where the previously controlled nation was never stored.

Evidence of influence resetting: https://www.youtube.com/watch?v=Lcw7DhtaExY (1 Windurst player was leveling in the region so it went to 0/0/100/0 for conquest influence)

The 5000 pool is not correct; you can't flip a region by exping in a zone for a few hours on retail. Additionally, it was/is difficult to flip the starter zones, something the 5000 pool does not restrict. The current influence does not carry over like how it's coded in LSB. This implementation will allow conquest to fit retail observably better than the current fixed implementation.

Steps to test these changes

Launch a new server, gain influence in a region or die so beastmen gain some, run the weekly tally !updateconquest 0 then !updateconquest 1.