APPCALL and TAILCALL unit tests

[shargon]

Also was Removed one unused method

[shargon]

I will add TAILCALL test before merge this Pull Request

[codecov-io]

Codecov Report

Merging #117 into master will increase coverage by 0.57%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #117      +/-   ##
==========================================
+ Coverage   80.09%   80.66%   +0.57%     
==========================================
  Files          45       45              
  Lines        4581     4578       -3     
==========================================
+ Hits         3669     3693      +24     
+ Misses        912      885      -27

Impacted Files	Coverage Δ
...sts/neo-vm.Tests/Extensions/ByteArrayExtensions.cs	100% <ø> (+27.27%)	⬆️
src/neo-vm/ExecutionEngine.cs	99.57% <0%> (+0.5%)	⬆️
src/neo-vm/Script.cs	100% <0%> (+8.06%)	⬆️
tests/neo-vm.Tests/Types/ScriptTable.cs	100% <0%> (+100%)	⬆️
tests/neo-vm.Tests/Types/VMUTScriptEntry.cs	100% <0%> (+100%)	⬆️

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