Fixed warning in unit tests, modified virtual function access for allocator

#649 Fixed the false positive 'array-bounds' errors for ETL unit tests.
#652 Fixed false positives 'maybe-uninitialized' errors for ETL unit tests.
Moved virtual functions in etl::fixed_sized_memory_block_allocator from private to protected.

Fixes, updates and new features

#615 Addition of etl::expected
#649 Changed intrusive_list and intrusive_forward_list iterator constructor parameter from reference to pointer.
#667 etl::span copy constructor with original span with fixed extent causes pend iterator to be invalid
#668 byte_stream changes that add error exceptions have changed previous behaviour
#670 span equality operators
#672 HFSM-specific start() and reset()
Fixed span templated copy constructor
Added destination_router_id parameter overrides to receive() virtual functions
Added ""_sv string view operators
Added M17 CRC
Added repair() to etl::circular_buffer
Added etl::contruct_object_at, etl::get_object_at and etl::destroy_object_at
Added etl::is_aligned, etl::alignment_exception and etl::alignment_error
Removed unnecessary code in etl::vector_ext::repair()
Updated sanity check make files
C++03 compatibility improvements

Added emplace by index to variant (variadic)

#660 byte_stream_reader::skip error

Emplace member functions return reference to emplaced value

20.35.10

Improved emplace testing

Minor updates

#657 -Wpedantic-failure. Removed superfluous semicolons
#653 CMake - Don't warn on tag missing when subproject
#651 result<T, void> specialization
#650 Fix result<void, E> default ctor
Removed Ubuntu 18.04 from Github Actions
Added Ubuntu 22.04 to Github Actions

Type traits improvements, etl::visit fix, removed unused macro

#648 Improve is_constructible, is_copy_constructible, is_move_constructible for type traits with default definitions
#645 Avoid 'missing return statement at end of non-void function' in etl::visit<>().
Removed unused ETL_USE_MEM_BUILTINS option

Updated etl::delgate to handle const functors correctly

Fixed C++03 specific conditional compilation in delegate header

#643 Don't use push_macro and pull_macro with Tasking compiler

20.35.6

#643 Don't use push_macro and pull_macro with Tasking compiler

Incorrect C++03 enable_if syntax

Incorrect C++03 enable_if syntax for etl::array_view and etl::span

#639 Only build tests if top level project

Changed CMakeLists.txt so that the ETL tests will only be built if it is the top level project.