Enable adding scripts with redeemers for withdrawals

[nielstron]

This has a usecase in the "withdrawal trick", where only one withdrawal is executed per transaction, checking overall invariants, and all inputs/mints by the script just check that the withdrawal is present.

[nielstron]

Note that ogmios v6 returns "withdraw:n" as the purpose for a withdrawal, so I changed the tag from "reward" to "withdraw". Not sure if ogmios v5 behaves differently.

Edit: removed from this PR

[codecov-commenter]

Codecov Report

Attention: 14 lines in your changes are missing coverage. Please review.

Comparison is base (8c3a12b) 83.42% compared to head (bb61a82) 83.09%.

Files	Patch %	Lines
pycardano/txbuilder.py	17.64%	13 Missing and 1 partial ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #308      +/-   ##
==========================================
- Coverage   83.42%   83.09%   -0.34%     
==========================================
  Files          28       28              
  Lines        3415     3431      +16     
  Branches      836      841       +5     
==========================================
+ Hits         2849     2851       +2     
- Misses        416      429      +13     
- Partials      150      151       +1     

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[nielstron]

I have confirmed that the REWARD tag is actually called WITHDRAWAL in Ogmios 5 and WITHDRAW in Ogmios 6. The current naming would thus break both the chain contexts either way. Blockfrost also returns WITHDRAWAL.

[nielstron]

Moreover there is only one place where the redeemer tag is actually used... which is within the transaction builder. So changing the value is most likely not breaking anything relevant. Anyways, I am open to move the change to a seperate PR

[cffls]

Thanks for checking! I am fine with the name changing in future PR.

[nielstron]

Note I removed this case because AFAIK it is impossible to enter this part of the branch. Mint redeemers can only be present in mint scripts, not in inputs.