Fix RET_CHECK crash in tflite_weight_accessor by returning proper Status errors

[SriHarsha-23]

Description

This PR addresses a stability issue in TfLiteWeightAccessor where loading incompatible or uninitialized models triggers a RET_CHECK failure, causing the application to crash (SIGABRT).

Context

As reported in #5600, using the Falcon CPU model on Android causes a hard crash due to dimension mismatches in quantized scale tensors. The current implementation uses RET_CHECK macros which terminate the process immediately upon failure.

Implementation

This change refactors LoadWeight and LoadTransposedWeight to replace fatal assertions with proper error handling:

• Replaced RET_CHECK macros with standard absl::InternalError (for uninitialized models) and absl::InvalidArgumentError (for dimension mismatches).
• Ensures the API returns a verifiable absl::Status that the caller can handle gracefully, rather than crashing the entire application.

Fixed Issue

Fixes #5600

Type of Change

• Bug fix (non-breaking change which improves reliability)

Test Plan

Static Verification: * Verified that the logic correctly implements absl::Status returns and adheres to C++ best practices.

• Confirmed clang-format Google style compliance.

CI/Build: * Relying on the repository's CI pipeline to verify the build against Android/iOS targets and run the regression suite, as the full cross-compilation environment is not available locally.

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[SriHarsha-23]

Hi @google-admin, I noticed the CI workflows are waiting for manual approval (Security Scan). Since this is my first contribution, I don't have permission to trigger them. Could a maintainer please approve the workflows so the tests can run? Thank you!