This patch introduces 3 modifications to the package MKL:

- added support of Fortran and GFortran to compile with the MKL
  libraries
- changed download paths following some changes made on the Intel
  channel of conda (see
  https://community.intel.com/t5/Intel-Integrated-Performance/Problems-installing-with-conda-HTTP-403-FORBIDDEN/m-p/1631577
  for details).
- added support of latest version of MKL as of September 2024: 2024.2.1

Note that the support of Intel processors on OS X seems to have been
dropped by Intel.  No path could be found.

Content of the repository can be parsed from the JSON files in each
architecture-dependent path:
https://software.repos.intel.com/python/conda/<arch>/repodata.json

with <arch> being one of the following:

- "linux-32"
- "linux-64"
- "win-32"
- "win-64"

Minimum example with GFortran:

Fortran code
```
program test_mkl

    use iso_fortran_env, only: real64

    integer, parameter :: N = 10
    integer :: info
    integer, dimension(N) :: iwork
    real(real64), dimension(N,N) :: A, B, C

    call random_number(A)
    call random_number(B)

    call dgemm('T','N',N,N,N,1.0_real64,A,N,B,N,0.0_real64,C,N)

    call dgetrf(N,N,C,N,iwork,info)

end program test_mkl
```

xmake.lua
```
add_rules("mode.debug", "mode.release")

add_repositories("local-repo xmake-repo")
add_requires("mkl", { configs = { threading = "gomp" } })

target("test_mkl")
    set_kind("binary")
    set_policy("check.auto_ignore_flags", false)
    add_packages("mkl")
    add_files("test_mkl.f90")
    add_tests("default")
```

The repository was also available in the new repository.
Versions listed in the package and not available in the repository have
been removed or replaced with more recent ones from the same year.

Fixed URLs to some Windows 32 packages and Linux
(32 and 64 bits) packages.

The tests to set the linker flags are now based on "ld/fcld" instead of
the compilers "cc/fc" to avoid problems with toolchains combining
different tools.

* Use of "" instead of '' for strings.
* Removal of unnecessary parentheses.
* Use of "local" for local variables.
* Removed unnecessary comments.

Previous patches incorrectly referred to the runtime configuration,
which is supposed to be built in and not set in package.

The variables for the linker with GFortran are now set to fcldflags and
fcshflags following the latest changes in xmake.

Some redundant or awkward constructs were also fixed.

Added Fortran test if gfortran available.

The test on the presence of gfortran may not guarantee the linker is
properly set.  The new test check that fcld is also set, for now to
gfortran since the test on the Fortran compiler only considers this
compiler.

Note: this way, fcsnippets are only run if --toolchain=gfortran is set.