How to use the new `default.tensor` quantum device

[PietropaoloFrisoni]

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Title: How to simulate quantum circuits with tensor networks using DefaultTensor

Summary: This how-to guide shows the first steps to use the new default.tensor device that will be available to users in PennyLane 0.37

Relevant references: To be discussed with reviewer(s)

Possible Drawbacks: None that I can think of, except for package dependencies

Related GitHub Issues: None

Related Shortcut Stories: [sc-65345]

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