Add support for RISC-V AIA IMSIC

[D3boker1]

RISC-V AIA APLIC support:

• Change the Bao's interrupt reservation mechanism;
• Add MSI Mode support in (V)APLIC driver;
• IMSIC driver.
• VIMSIC driver

Software Versions:

QEMU - v7.1.0 Linux - https://github.com/avpatel/linux/tree/riscv_aia_v1 OpenSBI - 1.2

[josecm]

@D3boker1 before starting the review I'd ask you to:

1. Resolve the conflicts with the main branch;
2. Make the history a little more granular, so we can better understand the structure of the introduced changes.

[josecm]

@ninolomata @DavidMCerdeira I believie this is ready to be merged. Please add your reviews.

@D3boker1 it would be great if you could also add your approval after my changes.

[D3boker1]

Hi @josecm!

I have tested these changes on AlSaqr SoC (dual-core version), and everything went smoothly. It looks great to me!