Find{BLAS,LAPACK}: Add libblastrampoline support

libblastrampoline is a BLAS/LAPACK demuxing layer to allow selecting a BLAS/LAPACK library at runtime. It includes both ILP64 and LP64 functions, and BLAS and LAPACK functions, so the same exact library is used for linking in every case.

We use this library extensively in the Julia ecosystem, and getting support in CMake makes building our binary ecosystem a lot easier.

I am going to say that this fixes my earlier issue, since now we can use the library without needing to override these variables.

Fixes: #25913 (closed)
Topic-rename: FindBLAS-LAPACK-libblastrampoline