Extract EFIBootServicesApplication events from PCR4 and validate EFI_ACTION as described in the spec

[yawangwang]

This PR does the following two things:

1. Adds support to extract EFIBootServicesApplication from PCR4 and populate them into FirmwareLogState.
2. Check the sequence of measuring the EFI_ACTION event “Booting to
   <Boot####> Option” in PCR4 conforming to the TCG PC Client Platform Firmware Profile Specification.
   • According to Section 8.4.2 step 4.a:

Upon selecting a boot device, the UEFI firmware measures the event type EV_EFI_ACTION “Calling EFI
Application from Boot Option” into PCR[4] and measures the event type EV_EFI_ACTION “Booting to
<Boot####> Option” where Boot#### is the Boot Option Variable Name.

[alexmwu]

I'm not sure this PR is necessary since we're checking the "Booting" event, but that is extraneous when we have the Calling EFI App event and it is unused.

[alexmwu]

Why are we returning these events?

[alexmwu]

This PR does the following two things:

1. Adds support to extract EFIBootServicesApplication from PCR4 and populate them into FirmwareLogState.

This already exists. This PR only does 2.

2. Validate the presence of the EFI_ACTION event “Booting to
   <Boot####> Option” found in PCR4 conforming to the TCG PC Client Platform Firmware Profile Specification.

   • According to Section 8.4.2 step 4.a:

Upon selecting a boot device, the UEFI firmware measures the event type EV_EFI_ACTION “Calling EFI
Application from Boot Option” into PCR[4] and measures the event type EV_EFI_ACTION “Booting to
<Boot####> Option” where Boot#### is the Boot Option Variable Name.

I'm not sure we need to validate this action unless we plan on extracting the boot variable option. The Calling EFI App event is sufficient.

[yawangwang]

Talked offline, this PR is unnecessary for now unless we plan to extract the boot variable option. Closing it.