feat: align common C API

[Jvlegod]

Hello maintainers,

This PR adds:

• version, arch_supported, and strerror, errno, context_size helpers
• context register r/w APIs(reg_r/w_batch, reg_r/w_bytes, reg_r/w_batch_bytes)
• TCG buffer size get and set operations(ctl_get_tcg_buffer_size, ctl_set_tcg_buffer_size)

Also I notice that in unicorn core's repo(https://github.com/unicorn-engine/unicorn/blob/master/include/unicorn/unicorn.h#L73)

// Unicorn API version
#define UC_API_MAJOR 2
#define UC_API_MINOR 1
#define UC_API_PATCH 4
// Release candidate version, 255 means the official release.
#define UC_API_EXTRA 255

// Unicorn package version
#define UC_VERSION_MAJOR UC_API_MAJOR
#define UC_VERSION_MINOR UC_API_MINOR
#define UC_VERSION_PATCH UC_API_PATCH
#define UC_VERSION_EXTRA UC_API_EXTRA

so I sync the code in unicorn_const.rs.

pub const API_MAJOR: u64 = 2;
pub const API_MINOR: u64 = 1;
pub const API_PATCH: u64 = 4;
pub const API_EXTRA: u64 = 255;
pub const VERSION_MAJOR: u64 = API_MAJOR;
pub const VERSION_MINOR: u64 = API_MINOR;
pub const VERSION_PATCH: u64 = API_PATCH;
pub const VERSION_EXTRA: u64 = API_EXTRA;
pub const SECOND_SCALE: u64 = 1_000_000;
pub const MILLISECOND_SCALE: u64 = 1_000;