Some updates for IntelVectorMath.jl

[ylvain]

I needed VML but stumbled on 2 problems with the current release 0.4.1

• The compat section reference MKL_jll 2020 and 2021, but MKL.jl use 2021, 2022. This was downgrading my MKL.
• In my use case, I need to handle threading myself and so I want VML to execute in a single thread.

The commits below fixe these issues. As I was at it I added control for denormal handling, tests, and a README update.

1. Change the compat to MKL 2021, 2022. This is what MKL.jl use on the current release 0.5.0
2. Add get/set for denormal mode handling and number of threads (impacting only VML, not BLAS/LAPACK etc.)
3. Version bump from 0.4.1 to 0.4.2.
4. Tests for the get/set, mention of these functions in the README.

[ylvain]

Hum... I notice only now that the other pending pull requests #54 actually has a commit for get/set numthreads... well... missed it, does not appear in the title/text, my bad. Anyway, mine as a doc-string :)

[Crown421]

My apologies, I was quite distracted last year. Currently looking through it, but seems quite solid.

[Crown421]

Looks good, great documentation.