evm: allow unencrypted calls

[nhynes]

This PR changes confidential EVM to accept all calls instead of just enveloped ones. This makes it easier to accidentally send public transactions, but it makes it harder for third-party tooling to integrate. We could make the gateway more restrictive instead of the runtime. The gateway would see a mistakenly unencrypted tx anyway.

[codecov]

Codecov Report

Merging #1256 (351f441) into main (5e03536) will increase coverage by 0.99%.
The diff coverage is 81.25%.

@@            Coverage Diff             @@
##             main    #1256      +/-   ##
==========================================
+ Coverage   66.94%   67.93%   +0.99%     
==========================================
  Files         132      133       +1     
  Lines       12317    12562     +245     
==========================================
+ Hits         8245     8534     +289     
+ Misses       4042     3998      -44     
  Partials       30       30              

Impacted Files	Coverage Δ
runtime-sdk/modules/evm/src/test.rs	67.62% <77.77%> (+0.31%)	⬆️
runtime-sdk/modules/evm/src/lib.rs	50.83% <85.71%> (+0.33%)	⬆️
runtime-sdk/src/callformat.rs	63.56% <0.00%> (-0.78%)	⬇️
contract-sdk/specs/token/oas20/src/types.rs	71.42% <0.00%> (ø)
contract-sdk/specs/token/oas20/src/lib.rs	58.25% <0.00%> (+58.25%)	⬆️
contract-sdk/specs/token/oas20/src/helpers.rs	78.97% <0.00%> (+78.97%)	⬆️

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[kostko]

Looks good!