Improve configurations persistence across different runs of the app

[GyulyVGC]

Improve configurations persistence across different runs of the app:

• support loading configurations from previous versions of Sniffnet even if the new release adds/changes some parameters
• persist all the configurations into a single TOML file
• more parameters are now persisted (in addition to the already persisted settings, device, and window properties):
  • capture source picklist
  • filters
  • inspect page table sort order
  • network hosts sort order
  • services sort order
  • last opened settings page
  • last opened running page
  • PCAP file export configurations
  • PCAP file import configurations

Fixes #507

[GyulyVGC]

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