Mock task pool surrealdb test

[unkcpz]

• use perform_sync and perform_async to wrap the block and return res/start_at/end_at
• update README with new run cmd.
• bring back the --number for insert many tasks at once.

[unkcpz]

The manual bench scale very good.

These are number of tasks I created

./target/release/actionwurm task add -n 20 --scale large -b async
./target/release/actionwurm task add -n 10000 --scale small -b async
./target/release/actionwurm task add -n 200 --scale medium -b sync
./target/release/actionwurm task add -n 500 --scale medium -b async
./target/release/actionwurm task add -n 20 --scale large -b sync

No block and fail or delay.