Convert license tags to SPDX identifiers

This commit also converts our own copyright headers to directly use
SPDX, but leaves all other copyright header intact, only adding the
SPDX ident. As far as possible this commit also merges multiple
Data61 copyright statements/headers into one for consistency.

mcs: add seL4_SchedContext_YieldTo

Implement seL4_SchedContext_YieldTo, which allows users to manipulate
the scheduling queues up to their MCP and can be used for user level
scheduling.

mcs: timeout exceptions

- Add seL4_TCB_SetTimeoutEndpoint
- implement timeout exceptions

style: consistently attach return type

Add attach-return-type to astyle

style: consistently align pointer with name

Run astyle with align-pointer=name

Fix licenses (the rest)

Change hasVCPU to generic archInfo boolean in public interfaces

The Arch_hasVCPU function instead of cheaking for whether a thread has a VCPU was
specifically checking for whether a thread on aarch32 had a VCPU, as that was the
condition needed to be passed into sanitiseRegister. This made the implementation
on x86 extremely confusing as Arch_hasVCPU was implemented to return false due to
there being no need for sanitiseRegister on x86 to know whether there was a vcpu.

This commit changes hasVCPU variables to be an abstract archInfo boolean that can
be used arbitrarily by an architecture. Arch_hasVCPU function was also changed to
become Arch_getSanitiseRegisterInfo whose result only passed to sanitiseRegister.

Refactor sanitiseRegister to take a bool rather than a (tcb_t *).

This involves adding a function to determine if a tcb has a vcpu, and
makes verification a lot easier for arm-hyp.

SELFOUR-836: Hardware debug API functions should take tcb_t and not arch_tcb_t

Touches files all throughout x86 (32 and 64) and ARM.

Pass tcb_t to sanitiseRegister instead of arch_tcb_t

s/D61/DATA61/ in license headers for consistency

arm: SELFOUR-781: Only allow threads with VCPU to run outside user mode

Previously any thread could be set to run in any mode (except HYP mode).
Whilst this causes no security issues for the kernel, different execution
modes in ARM have different banked registers. These registers are not
currently saved and restored allowing for threads to manipulate registers
that will be seen (or potentially are being actively used) by other threads.

Saving and restoring these banked registers for all threads is a performance
cost (even if only done for the actual mode the thread runs in) for no real
benefit, as there is no clear reason to run a thread in other modes if you
do not have a vcpu. Therefore this commit restricts being in modes other than
user to threads that have a vcpu. When multiple VCPUs are properly supported
the switching of VCPUs will then save/restore these banked registers.

SELFOUR-413: changes for verification

Avoid using ptrs to arrays at all

Another macrofull change brought to your by verification. This should
avoid nasty proofs about const pointers.

SELFOUR-413: refactor libsel4 fault API

This is a *breaking API change*

This commit:

* makes seL4_Fault_tag_t common between the kernel and libsel4
* deprecates the existing functions from sel4/messages.h includes
* introduces a new fault API in sel4/faults.h and
* sel4/sel4_arch/faults.h
* deprecates seL4_GetTag(), as the function did not work without
the user calling seL4_SetTag() first (seL4_MessageInfo is passed
in registers and not set in the IPC buffer)
* removes previously deprecated functions (deprecated prior to 3.0.0)
* updates the seL4 manual to reflect the changes

Split fault types into arch/generic

Prior to this commit faults were separate
per architecture. This commit extracts the common
fault types and introduces arch specific faults,
reducing code duplication across architectures.