refactor: improve the public interface by using triats

[SteveLauC]

What does this PR do

1. Replace argument type &str with S: AsRef<str>
2. Replace argument type &[u8] with B: AsRef<[u8]

With the usage of traits, these public interfaces can accept more types, take S: AsRef<str> as an example, you can pass the following types to it:

1. &str
2. String
3. &String
4. ...

and will thus be more ergonomic and rusty

[SteveLauC]

BTW, there is a test failure:

test test_get_language_extensions ... FAILED

failures:

---- test_get_language_extensions stdout ----
-------------- TEST START --------------
thread 'test_get_language_extensions' panicked at 'assertion failed: `(left == right)`
  left: `[".py", ".cgi", ".fcgi", ".gyp", ".gypi", ".lmi", ".py3", ".pyde", ".pyi", ".pyp", ".pyt", ".pyw", ".rpy", ".spec", ".tac", ".wsgi", ".xpy"]`,
 right: `[".py", ".cgi", ".fcgi", ".gyp", ".gypi", ".lmi", ".py3", ".pyde", ".pyi", ".pyp", ".pyt", ".pyw", ".rpy", ".smk", ".spec", ".tac", ".wsgi", ".xpy"]`', tests/test_enry.rs:183:5
stack backtrace:
   0: rust_begin_unwind
             at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/std/src/panicking.rs:593:5
   1: core::panicking::panic_fmt
             at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/core/src/panicking.rs:67:14
   2: core::panicking::assert_failed_inner
   3: core::panicking::assert_failed
             at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/core/src/panicking.rs:229:5
   4: test_enry::test_get_language_extensions::test_get_language_extensions
             at ./tests/test_enry.rs:183:5
   5: test_enry::test_get_language_extensions
             at ./tests/test_enry.rs:176:1
   6: test_enry::test_get_language_extensions::{{closure}}
             at ./tests/test_enry.rs:176:1
   7: core::ops::function::FnOnce::call_once
             at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/core/src/ops/function.rs:250:5
   8: core::ops::function::FnOnce::call_once
             at /rustc/d5c2e9c342b358556da91d61ed4133f6f50fc0c3/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

failures:
    test_get_language_extensions

But since this repo is just about bindings, it is probably something changed in the upstream