Rework VFIO Tests

[sol-0]

Issue

We have multiple test case stability issues:

• VFIO tests are unstable #278
• unit test TestVFIOServer_Request is unstable on ci #330
• unit test TestVFIOServer_Close is unstable on ci #333

In order to increase tests stability, test infrastructure and reading/writing from files and pipes (file API) should be reworked as the root cause is related to I/O operations not being fast enough to complete during the limited test time.

When we tried to fix the issue #330, it turned out that even 300 ms timeout was not good enough to guarantee the test stability.