Create new `zcash_script` crate that will contain logic for verifying Zcash transparent scripts.

[ebfull]

This is a very early WIP attempt at recreating zcashd's CScript interpreter and other logic needed to verify transparent scripts in an attempt to destroy this directory and help out the Zebra folks who maintain the actual zcash_script crate which binds to our C++ codebase.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 306 lines in your changes are missing coverage. Please review.

Project coverage is 73.59%. Comparing base (4d28279) to head (409c8aa). Report is 1497 commits behind head on main.

Files	Patch %	Lines
zcash_script/src/lib.rs	0.00%	254 Missing :warning:
zcash_script/src/opcodes.rs	0.00%	52 Missing :warning:

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #655       +/-   ##
===========================================
+ Coverage   51.52%   73.59%   +22.06%     
===========================================
  Files          91      101       +10     
  Lines        8500    10825     +2325     
===========================================
+ Hits         4380     7967     +3587     
+ Misses       4120     2858     -1262     

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[nuttycom]

Subsumed by https://github.com/ZcashFoundation/zcash_script/pull/158