Change serde_json::from_value to use pass-by-reference

[rooney]

If the function needs ownership, you should pass by value. If the function only needs a reference, you should pass by reference.

-- https://stackoverflow.com/a/64814149/342293

from_value doesn't need to own its parameter, so it should use pass-by-reference.

[GnomedDev]

Is this not an obvious breaking change that would require a serde_json 2.0?

[rooney]

Is this not an obvious breaking change that would require a serde_json 2.0?

Hmm yes, any other parts that should also been updated? (Apologies if these should be obvious, still learning)

[rooney]

@GnomedDev Redone the fix so now from_value accepts both &Value and Value (so no breaking changes, but maybe the latter can be deprecated?). New test for the &Value is on doctest (should I add more?)