VENOM-358: Change app namespace

[naxuroqa]

• Update flatpak manifest to toxcore 0.2.2
• Use git tags in flatpak
• Move all references to im.tox. to chat.tox.

[codecov-io]

Codecov Report

Merging #358 into develop will not change coverage. The diff coverage is 0%.

@@           Coverage Diff            @@
##           develop     #358   +/-   ##
========================================
  Coverage    38.08%   38.08%           
========================================
  Files           49       49           
  Lines         2846     2846           
========================================
  Hits          1084     1084           
  Misses        1762     1762

Impacted Files	Coverage Δ
src/core/R.vala	0% <0%> (ø)	:arrow_up:

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