[enhancement] Strict/Proper URI decoding/encoding

[syoyo]

Describe the issue

glTF uses URI for its asset path.

KhronosGroup/glTF#1744
https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#uris

Currently TinyGLTF implements simple URI decoding only:

tinygltf/tiny_gltf.h

Line 2203 in 9117abb

// TODO(syoyo): Use uriparser https://uriparser.github.io/ for stricter Uri

Proper and strict URI decoding/encoding are recommended.
urlparser https://uriparser.github.io/ Could be a good candidate to handle URI path.

Also, it would need to provide a way to handle absolute URI(e.g. URI containing http prefix) through FS callback.

To Reproduce

• OS
  Any
• Compiler, compiler version, compile options
  Any
• Please attach minimal and reproducible .glTF file if you got an issue related to .glTF data
  N/A

Expected behaviour

TinyGLTF decodes/encodes URIs correctly.

We may need glTF files containing various URIs to test.

[syoyo]

Providing strict URI parser may be difficult. For a while, let App/User write their own URI encoder/decoder. tinygltf now has URI callbacks thanks to: #397