Replace the HomeDir flag with a AppDir flag

[elichai]

#1613 restructured the default directory, but used the name homedir to represent it, which is ambiguous with ~/ or $HOME.
so this renames it to appdir which should be less ambiguous

[codecov]

Codecov Report

Merging #1615 (964a4b3) into v0.10.0-dev (1a4161f) will increase coverage by 0.02%.
The diff coverage is 25.00%.

❗ Current head 964a4b3 differs from pull request most recent head 5cf1284. Consider uploading reports for the commit 5cf1284 to get more accurate results

@@               Coverage Diff               @@
##           v0.10.0-dev    #1615      +/-   ##
===============================================
+ Coverage        59.98%   60.01%   +0.02%     
===============================================
  Files              515      515              
  Lines            20454    20454              
===============================================
+ Hits             12270    12275       +5     
+ Misses            6234     6229       -5     
  Partials          1950     1950              

Impacted Files	Coverage Δ
app/app.go	0.00% <0.00%> (ø)
cmd/kaspaminer/config.go	0.00% <ø> (ø)
infrastructure/config/config.go	11.11% <16.66%> (ø)
util/appdata.go	86.66% <100.00%> (ø)
infrastructure/network/addressmanager/store.go	78.30% <0.00%> (+1.88%)	⬆️
...ersselectedchainstore/headersselectedchainstore.go	71.02% <0.00%> (+2.80%)	⬆️

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