Add support for decoding ENDBR32/64 instructions

[rafaelroquetto]

The ENDBR32 and ENDBR64 (collectively ENDBRANCH) are two new instructions that are used to mark valid indirect CALL/JMP target locations in the program. This instruction is a NOP on legacy processors for backward compatibility.

The processor implements a state machine that tracks indirect JMP and CALL instructions. When one of these instructions is seen, the state machine moves from IDLE to WAIT_​FOR_​ENDBRANCH state. In WAIT_​FOR_​ENDBRANCH state the next instruction in the program stream must be an ENDBRANCH. If an ENDBRANCH is not seen the processor causes a control protection fault (#CP), otherwise the state machine moves back to IDLE state.

(Source)

At this time, https://pkg.go.dev/golang.org/x/arch/x86/x86asm does not support decoding these instructions. We add a workaround that manually skips over them until proper support is added.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.90%. Comparing base (9efc255) to head (c35a5a8).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1416      +/-   ##
==========================================
+ Coverage   72.41%   80.90%   +8.49%     
==========================================
  Files         145      146       +1     
  Lines       14868    14891      +23     
==========================================
+ Hits        10766    12048    +1282     
+ Misses       3389     2252    -1137     
+ Partials      713      591     -122     

Flag	Coverage Δ
integration-test	59.10% <78.57%> (-0.03%)	⬇️
k8s-integration-test	60.01% <78.57%> (-0.01%)	⬇️
oats-test	34.00% <78.57%> (+0.11%)	⬆️
unittests	51.56% <78.57%> (?)

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[grcevski]

LGTM! Awesome!