Add system memory resource

[rongou]

Description

Adds a new device memory resource that uses system allocated memory. Works around some existing issues when GPU memory is oversubscribed.

closes #1580

Checklist

• [x] I am familiar with the Contributing Guidelines.
• [x] New or existing tests cover these changes.
• [x] The documentation is up to date with these changes.

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[wence-]

/ok to test

[wence-]

/ok to test

[harrism]

/ok to test

Does this mean @rongou doesnt have commit signing set up?

[wence-]

/ok to test

Does this mean @rongou doesnt have commit signing set up?

Looks like it, yes. @roungou: these docs describe how to set this up https://docs.github.com/en/authentication/managing-commit-signature-verification/about-commit-signature-verification

[wence-]

/ok to test

[rongou]

Ok, signed the commits.

[harrism]

/merge