New X4 instance type

[github-actions]

Machine types 'machinetypes.csv' changed

Added:
x4-megamem-1440-metal;1440;False;24576.00;;
x4-megamem-1920-metal;1920;False;32768.00;;
x4-megamem-960-metal;960;False;16384.00;;

Deleted:

Todo:

• Check changes
• Edit title of this issue
• Run build/skus.sh workflow to export SKUs from the Google Cloud Billing API
• Check if machine type is present in 'build/skus.db'
• Add or remove mapping in build/mapping.csv
• Add or remove the machine type in build/gcp.yml
• Add or remove the machine type with mapping in build/pricing.pl
• Check if machine type gets SUD and edit build/pricing.pl
• Create a test for machine type in t/test.sh
• Test cost calculation with machine type
• Build new pricing information file 'pricing.yml'
• Run Build action in Cyclenerd/google-cloud-compute-machine-types

[Cyclenerd]

Available for "ordering": https://cloud.google.com/compute/docs/memory-optimized-machines#x4_series
No public price list: Contact your Google Cloud account manager for pricing and ordering information for X4, or to discuss on-demand pricing for testing X4 instances.

[Cyclenerd]

#176