Fix warnings, exceptions, improve some UI elements

[Fort-TM]

I saw someone having issues with the plugin on the Openplanet Discord, so I tried to take a look and fix other issues I found

• Addresses all sanity warnings when loading the plugin
• Fixed invalid icon for settings tab
• Fixed 2 exceptions related to JSONs. One when first using the plugin, another when fetching PVMs. For the latter, now the plugin tries to fetch the JSON up to 5 times (with a cooldown), and checks the JSON type before doing anything with it
• Fixed text alignment for the search bar and the table rows
• Made it so the "Show Overview" button toggles the overlay, instead of simply opening it
• Made progress bar take full width regardless of the window size

• Fixed an Imgui warning due to buttons using the same name