libinjector: skip kernel mode trap frame and split wait_for_target_process_cb

[psrok1]

Following the discussion from #1639

• Splitted part of wait_for_target_process_cb into setup_usermode_trap_x86 and setup_usermode_trap_x64 to reduce cognitive complexity within that function
• Fixed bug in setup_usermode_trap_x64 that catched kernel-mode address from trap frame. It was rare case and probably related to page fault inside kernel.
• Added description to setup_usermode_trap_x86 explaining why we need to use different methods on x64 and x86.

[drakvuf-jenkins]

Can one of the admins verify this patch?

[tklengyel]

@drakvuf-jenkins Test this please

[tklengyel]

Thanks!