MdeModulePkg/PciBusDxe: Add optional CRS retry for enumeration

The current PciDevicePresent() implementation skips PCIe devices that
return Configuration Request Retry Status (CRS) during enumeration.
This causes devices that are slow to initialize (e.g., after power-on
or reset) to be missed entirely.

Per PCIe Base Specification Rev 3.1 Section 2.3.1, when CRS Software
Visibility is enabled and a device returns CRS, the Root Complex
reports Vendor ID as 0x0001. The specification recommends software
retry the configuration read until the device becomes ready.

This patch adds optional CRS retry support controlled by PCDs:

- PcdPciCrsRetryIntervalUs: Retry interval in microseconds (default 10000)
- PcdPciCrsTimeoutSeconds: Total timeout in seconds (default 0)

By default (PcdPciCrsTimeoutSeconds=0), CRS retry is disabled and
devices returning CRS are skipped during enumeration. Platforms
requiring CRS retry support should set PcdPciCrsTimeoutSeconds to
a non-zero value.

Additional improvements:
- Add PCI_VENDOR_ID_NONE and PCI_VENDOR_ID_CRS macros for readability
- Handle invalid PCD configurations (e.g., zero retry interval)
- Add DEBUG output for CRS detection, successful retry, and timeout

Signed-off-by: Ashish Singhal <ashishsingha@nvidia.com>