Implement workaround for initialization order errors in JVM lambdas

[armanbilge]

Fixes a regression reported on Discord.

Previously, IOLambda was not sensitive to whether initializing the handler involved vals. This is because the definition of handler was used lazily on the first invocation of the lambda, not during its construction.

However, after the changes in #446, we now use the definition of handler eagerly during construction. A val in a superclass (i.e. IOLambda) is always initialized before vals in the subclass (i.e. user-defined FooLambda). This means that all vals in the subclass are uninitialized (i.e. null) when we initialize val handle in IOLambda.

The proper remedy for this situation is that users should always use def instead of val in their IOLambdas. However, because this is a highly surprising regression wrt the previous behavior, we now make a best-effort to detect this situation, log an actionable warning, and fallback to the old semantic where we initialize during the first invocation of the lambda.

There was an error initializing `FooLambda` during startup.
Falling back to initialize-during-first-invocation strategy.
To fix, try replacing any `val`s in `FooLambda` with `def`s.

I've published this PR as 0.3-97de28d-SNAPSHOT.

[armanbilge]

There will be an official way to do this soon.

• Add a memoizedAcquire method to Resource cats-effect#3890