Improve VM SKU documentation and errors

[jemrobinson]

:white_check_mark: Checklist

• [x] You have given your pull request a meaningful title (e.g. Enable foobar integration rather than 515 foobar).
• [x] You are targeting the appropriate branch. If you're not certain which one this is, it should be develop.
• [x] Your branch is up-to-date with the target branch (it probably was when you started, but it may have changed since then).

:vertical_traffic_light: Depends on

n/a

:arrow_heading_up: Summary

IMPORTANT: I am confident that merging this will not affect the findings of the ongoing penetration test

• Add note to documentation explaining that premium-SSD-compatible VMs must be used
• Improve logging of Pulumi errors so that this also appears in the logs:

 stderr:
Pulumi error: +  azure-native:compute:VirtualMachine sre_workspaces_vm_workspace_02 creating (3s)  Code="InvalidParameter" Message="Requested operation cannot be performed because the VM size Standard_D8_v5 does not support the storage account
type Premium_LRS of disk 'shm-pink-sre-coral-vm-workspace-02-osdisk'. Consider updating the VM to a size that supports Premium storage." Target="osDisk.managedDisk.storageAccountType"
Pulumi error: +  azure-native:compute:VirtualMachine sre_workspaces_vm_workspace_02 **creating failed**  Code="InvalidParameter" Message="Requested operation cannot be performed because the VM size Standard_D8_v5 does not support the storage
account type Premium_LRS of disk 'shm-pink-sre-coral-vm-workspace-02-osdisk'. Consider updating the VM to a size that supports Premium storage." Target="osDisk.managedDisk.storageAccountType"
Pulumi error:    pulumi:pulumi:Stack data-safe-haven-shm-pink-sre-coral running  update failed
Pulumi error:  Code="InvalidParameter" Message="Requested operation cannot be performed because the VM size Standard_D8_v5 does not support the storage account type Premium_LRS of disk 'shm-pink-sre-coral-vm-workspace-02-osdisk'. Consider
updating the VM to a size that supports Premium storage." Target="osDisk.managedDisk.storageAccountType"
Pulumi error:  update failed
Pulumi update failed.
Pulumi deployment failed.
Could not deploy Secure Research Environment 'coral'.

:closed_umbrella: Related issues

Closes #2067

:microscope: Tests

Tested by trying to add an incompatible VM to an existing SRE

[github-actions[bot]]

Coverage report

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File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
data_safe_haven/infrastructure
project_manager.py					277
Project Total

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