Uninitialized data access issue fixed

[olesHolem]

What ❔

This PR adds data_is_set field to structures AsyncVec and DeviceBuf to track if inner data is correct and defined.

Why ❔

Currently, it's possible to get access to uninitialized data. The simplest way is through allocate_new and get_values method of AsyncVec.

[github-actions]

Hey there! 👋🏼

We require pull request titles to follow the Conventional Commits specification and it looks like your proposed title needs to be adjusted.
Examples of valid PR titles:

• feat(boojum-cuda): Expose more public methods
• fix(gpu-ffi): Correctly handle edge case
• ci: Add new workflow for linting

Details:

No release type found in pull request title "Uninitialized data access issue fixed". Add a prefix to indicate what kind of release this pull request corresponds to. For reference, see https://www.conventionalcommits.org/

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[robik75]

@olesHolem Do you still want to include merge this PR or should we close it?