[msl] Add new port

[Mickyas Tesfaye (Alazar42)]

Description

This PR adds the new port msl (Melkam Standard Library) version 1.0.0.

Melkam Standard Library (MSL) is a modern, high-performance, memory-safe, header-only C++20 utility and math library providing core data types (Array<T>, String, Color, Vector2, Vector3).

• Upstream repository: https://github.com/Alazar42/MSL
• License: MIT

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Checklist

• Changes comply with the maintainer guide.
• The packaged project is mature and ready for broad sharing with vcpkg users
  • Some other reason: Initial release of Melkam Standard Library (MSL) providing header-only C++20 math and data structure primitives.
• The packaged project shows strong association with the chosen port name. Check this box if at least one of the following criteria is met:
  • The port name follows the 'GitHubOrg-GitHubRepo' form or equivalent Owner-Project form (Alazar42/MSL).
• Optional dependencies of the build are all controlled by the port.
• The versioning scheme in vcpkg.json matches what upstream says (1.0.0).
• The license declaration in vcpkg.json matches what upstream says (MIT).
• The file installed as the "copyright" file matches what upstream says (LICENSE).
• The source code of the component installed comes from an authoritative source (https://github.com/Alazar42/MSL/archive/v1.0.0.tar.gz).
• The generated "usage text" is brief and accurate.
• The version database is fixed by running vcpkg x-add-version msl and committing the result.
• Exactly one version is added in each modified versions file (versions/m-/msl.json and versions/baseline.json).

[Billy O'Neal (BillyONeal)]

• The packaged project is mature and ready for broad sharing with vcpkg users
  • Some other reason: Initial release of Melkam Standard Library (MSL) providing header-only C++20 math and data structure primitives.

This isn't really a justification; the repo in question is 1 day old and doesn't meet any of the usual guidelines to be put in vcpkg's default registry as noted in the maintainer guide.

• The packaged project shows strong association with the chosen port name. Check this box if at least one of the following criteria is met:
  • The port name follows the 'GitHubOrg-GitHubRepo' form or equivalent Owner-Project form (Alazar42/MSL).

"MSL" is not "GitHubOrg-GitHubRepo"; that would be alazar42-msl. In particular, that name is already associated in repology to https://github.com/akb825/ModularShaderLanguage .

[Billy O'Neal (BillyONeal)]

Suggested change

	include("${VCPKG_ROOT_DIR}/ports/vcpkg-cmake/vcpkg-port-config.cmake" OPTIONAL)
	include("${VCPKG_ROOT_DIR}/ports/vcpkg-cmake-config/vcpkg-port-config.cmake" OPTIONAL)

These functions are made available when you add the dependencies correctly. I don't even think {VCPKG_ROOT_DIR} is a thing and OPTIONAL is hiding that this never does anything.