ndk: Add definitions and bindings for API levels

[MarijnS95]

android/api-levels.h from the NDK defines constants for all (NDK-supported) API levels and both a getter for the "current apps' target API level" as well as the API level of the device the app is running on. Create bindings to allow users to query this information at runtime from their Rust code as well.

The equivalent of the NDK's __ANDROID_API__ define are our api-level-xx crate features, used to restrict APIs (and inexistant linker symbols) at build-time.
(As there is no full-fledged Android build system involved, users of the ndk crate are expected to keep this in sync with the minimum/target API level passed to their build tool of choice.)

[MarijnS95]

CC @daxpedda

[MarijnS95]

error: struct `crash_detail_t` is never constructed
     --> ndk-sys/src/ffi_aarch64.rs:16024:12
      |
16024 | pub struct crash_detail_t {
      |            ^^^^^^^^^^^^^^
      |
      = note: `-D dead-code` implied by `-D warnings`
      = help: to override `-D warnings` add `#[allow(dead_code)]`

error: struct `ACameraOutputTargets` is never constructed
     --> ndk-sys/src/ffi_aarch64.rs:21233:12
      |
21233 | pub struct ACameraOutputTargets {
      |            ^^^^^^^^^^^^^^^^^^^^

I think this is a Rust 1.80 clippy false-positive. The types may not be constructed by us, but they are pub visible and could be used in downstream code.

However, no API currently takes these symbols, so we might as well skip & hide them until they become useful?

(ACameraOutputTarget without -s does exist and is used)

[MarijnS95]

Re-running CI jobs because some changes to dead_code causing these false-positives appear to have been reverted in 1.80.1: https://blog.rust-lang.org/2024/08/08/Rust-1.80.1.html#false-positives-in-the-dead_code-lint