Allow configuring CPU usage during SEG-Y import/export

[tasansal]

Overview

This PR includes modifications to the blocked_io.py and mdio.py scripts to enhance CPU utilization reconfigurability through environment variables.

The MDIO__IMPORT__CPU_COUNT and MDIO__EXPORT__CPU_COUNT allow users to specify how many cores to use.

If the variables don't exist, it will use all the available cores of the machine.

Changes in blocked_io.py

• Replaced the NUM_CORES definition with a more flexible approach:

default_cpus = cpu_count(logical=True)
NUM_CPUS = int(os.getenv("MDIO__IMPORT__CPU_COUNT", default_cpus))

Changes in mdio.py

• Introduced environment variable for CPU count configuration:

default_cpus = cpu_count(logical=True)
NUM_CPUS = int(os.getenv("MDIO__EXPORT__CPU_COUNT", default_cpus))

Summary

These changes aim to provide better control over CPU usage through environment variables.