refactor: Add common Hathor types

[msbrogli]

Acceptance criteria

1. Create the common Hathor types: TxId, Address, TxOutputScript, Timestamp, TokenUid, and Amount.
2. Refactor hathor.manager, hathor.transaction.base_transaction, and hathor.transaction.transaction as the initial refactor.

[codecov]

Codecov Report

Merging #642 (a3e3740) into master (c68cc37) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head a3e3740 differs from pull request most recent head e29a919. Consider uploading reports for the commit e29a919 to get more accurate results

@@            Coverage Diff             @@
##           master     #642      +/-   ##
==========================================
+ Coverage   84.03%   84.05%   +0.01%     
==========================================
  Files         244      245       +1     
  Lines       20262    20272      +10     
  Branches     2759     2759              
==========================================
+ Hits        17027    17039      +12     
+ Misses       2637     2635       -2     
  Partials      598      598              

Impacted Files	Coverage Δ
hathor/manager.py	69.78% <100.00%> (+0.04%)	⬆️
hathor/transaction/base_transaction.py	91.44% <100.00%> (+0.01%)	⬆️
hathor/transaction/transaction.py	92.68% <100.00%> (+0.02%)	⬆️
hathor/types.py	100.00% <100.00%> (ø)
hathor/util.py	84.59% <100.00%> (+0.65%)	⬆️

... and 3 files with indirect coverage changes