[oneMKL][DFT] Full revision of DFT parts of specs + addition of {F,B}WD_STRIDES configuration parameters (#506)

* [DFT] removing REAL_COMPLEX and CCE_FORMAT from the list of config_value as 1) this is the only appearance of REAL_COMPLEX found in the sources (the specs lack much clarification about it if we keep it there), 2) the changes targeted herein - addition of {F,B}WD_STRIDES - would result in even more nightmare-ish additions of other formats than CCE_FORMAT (and clarifications thereof) that would be supported only for 1D real transfomrs on CPU devices by closed-source oneMKL anyways... Also removing config_param::PACKED_FORMAT as its very existence is questionable (and confusing imo) if CCE is the only format registered in the specs for conjugate-even complex sequences anyways

* [DFT] Revisions to the landing page, introducing and generalizing notations to be used thereafter

* [DFT] Revisions to descriptor page + introduction of jargon therein to refer to it thereafter.

* [DFT] Revision to the page for scoped enumeration types + removing the page about {FOR|BACK}WARD_SCALE as it doesn't add any relevant information that is not already specified therein

* [DFT] Revisions to the page for data layout configuration and integrating all specs pertaining to batched DFTs therein to make it self-contained (removing number_of_transforms.rst)

* [DFT] specializing compute_forward call in REAL_REAL example from storage_formats to avoid ambiguity.

* [DFT] removing WORKSPACE configuration parameter and corresponding values

---------

Co-authored-by: Parks, Helen <[email protected]>
Co-authored-by: Finlay <[email protected]>

Author: 3 people

source/elements/oneMKL/source/architecture/api_design.inc.rst

@@ -23,7 +23,7 @@ namespace                 oneMKL domain or content
 ``oneapi::mkl::blas``     Dense linear algebra routines from BLAS and BLAS like extensions. The oneapi::mkl::blas namespace should contain two namespaces column_major and row_major to support both matrix layouts. See :ref:`onemkl_blas`
 ``oneapi::mkl::lapack``   Dense linear algebra routines from LAPACK and LAPACK like extensions. See :ref:`onemkl_lapack`
 ``oneapi::mkl::sparse``   Sparse linear algebra routines from Sparse BLAS and Sparse Solvers. See :ref:`onemkl_sparse_linear_algebra`
-``oneapi::mkl::dft``      Discrete and fast Fourier transformations. See :ref:`onemkl_dft`
+``oneapi::mkl::dft``      Discrete Fourier Transforms. See :ref:`onemkl_dft`
 ``oneapi::mkl::rng``      Random number generator routines. See :ref:`onemkl_rng`
 ``oneapi::mkl::vm``       Vector mathematics routines, e.g. trigonometric, exponential functions acting on elements of a vector. See :ref:`onemkl_vm`
 ========================  =======================================================================================================