SSH private key not validated on updateProject

[smlx]

Describe the bug
Using the updateProject mutation you can set the private key field to any string. This will cause operations using that key to fail.

To Reproduce
Steps to reproduce the behavior:

1. Use the updateProject mutation, providing an invalid private key.
2. Mutation succeeds.
3. Inspect the project, and see that it has an invalid private key.

Expected behavior
I expected the SSH key to be validated in some way. It doesn't even have to be fully parsed if that is expensive, just check that the first line is the correct format.

Screenshots
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Additional context
n/a