fix: remove download dependency from manta-benchmark

[BoyuanFeng]

Summary

Fix compatibility issue between manta-benchmark and manta-parameters/download.

Details

openssl is not well-supported yet in wasm. manta-parameters use openssl to download lfs files while manta-benchmark contains wasm benchmarks. Currently, manta-benchmark implicitly imports openssl through manta-pay/test which imports manta-parameters/download.

In this PR, we separate the feature manta-parameters/download from manta-pay/test to avoid this implicit import of openssl in manta-benchmark.

Issue: #104

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