partial fill block + UX improvements

[zeroXbrock]

• remove timeout from spammer
• add env var C_FILL_PERCENT to fill blocks up to a given percent when the fill-blocks scenario is run with contender run
• add stress.toml, tweak mempool.toml
• cleanup logs
• don't crash on failed tasks
• graceful CTRL-C termination (so you can get your run_id even if you need to terminate)
• accurately estimate gas limits (differ by calldata)

Motivation

partial fill-block:

in case you want to fill a block up to <100%

the rest:

• don't crash the whole run because of one failed tx
• stop early and still save results
• get more info about your txs and their execution status
• accurate gas estimates mean more txs will fit in a block
• new scenario spams more opcodes (even more are available in the contract)

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes