Use log returns for Sharpe and Sortino

[ferranbt]

No description provided.

[ferranbt]

Closing this since the consistent way in Pinescript is to do it with arithmetic sums.

[codspeed-hq]

Merging this PR will not alter performance

✅ 74 untouched benchmarks

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_{Comparing fix-sharpe-indicator (f2d9aea) with main (9f3fd46)¹}

Footnotes

1. No successful run was found on main (c901a09) during the generation of this report, so 9f3fd46 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩