feat[lang]: introduce mana as an alias for gas

[pcaversaccio]

What I did

In light of EIP-6789, I introduce mana as an alias for gas. Since mana is so far only an alias, I do deliberately not replace all the gas kwargs nor any other gas keywords in the documentation with mana.

How I did it

I introduce a new transaction property called msg.mana that is semantically the same as msg.gas.

How to verify it

• EIP-6789

Commit message

per EIP-6789 (https://eips.ethereum.org/EIPS/eip-6789), add `msg.mana`
as an alias for `msg.gas`

Description for the changelog

Introduce mana as an alias for gas.

Cute Animal Picture

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.60%. Comparing base (24cfe0b) to head (6ccc25a).

❗ Current head 6ccc25a differs from pull request most recent head 162c444

Please upload reports for the commit 162c444 to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3713      +/-   ##
==========================================
- Coverage   91.26%   88.60%   -2.66%     
==========================================
  Files         109      106       -3     
  Lines       15552    15288     -264     
  Branches     3417     3367      -50     
==========================================
- Hits        14193    13546     -647     
- Misses        929     1230     +301     
- Partials      430      512      +82     

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[charles-cooper]

interesting PR, i need to meditate on this one!

[charles-cooper]

note that after EOF, there won't be any references to gas within the EVM, so there may not be anything to do here

[charles-cooper]

one change!