Add ADI VNA 8 channels project

[zahitevrenkaya]

PR Description

Initial version of 8ch VNA HDL implementation. The design is based on the 4ch HDL design.

One type of CW about ad_3w_spi was coming from a component which is used in the same way it was being used in 4ch design. Therefore, I kept it as it is. HW was functioning as expected.

PR Type

• Bug fix (change that fixes an issue)
• New feature (change that adds new functionality)
• Breaking change (has dependencies in other repos or will cause CI to fail)

PR Checklist

• I have followed the code style guidelines
• I have performed a self-review of changes
• I have compiled all hdl projects and libraries affected by this PR
• I have tested in hardware affected projects, at least on relevant boards
• I have commented my code, at least hard-to-understand parts
• I have signed off all commits from this PR
• I have updated the documentation (wiki pages, ReadMe files, Copyright etc)
• I have not introduced new Warnings/Critical Warnings on compilation
• I have added new hdl testbenches or updated existing ones

[AndreiGrozav]

Please delete in another commit the ad9083_vna project from this repo, since it was the initial version of the 8ch VNA.