Enhance client behavior for loadtest suite

[GeorgeTsagk]

Description

Our current suite for the loadtest setup connects to 2 clients and mints batches of collectible assets. Then proceeds to send one asset back and forth multiple times. This is sufficient for monitoring the resource usage during minting/sending, but could be extended to cover more parts of the RPC/codebase.

Proposed Changes

• Add normal assets to the mix, with varying supplies and dec_displays.
• Send a random amount of a random asset on each send
• Pick an asset that is fixed across test runs, which is always picked by clients and is costantly sent back and forth
  • Having this break-away asset will help us compare its resource footprint to the rest of the "common" assets, plus understand it's impact on the overall system (could eventually burn this asset after N sends or until proof size reaches size X)
• For the common assets, we should follow an exponential course instead of a linear one. Currently we mint/send a fixed number of assets per run. We could change this to 1.1*X where X is the number of assets minted in the previous run.