Sign conversion errors in VariableLengthArray

[skeetsaz]

include/cetl/variable_length_array.hpp:2339:82: error: conversion to ‘unsigned int’ from ‘int’ may change the sign of the result [-Werror=sign-conversion]
                     const std::size_t bit_size_delta = 8U - (last_byte_bit_fill_ + 1);
                                                             ~~~~~~~~~~~~~~~~~~~~~^~~~
include/cetl/variable_length_array.hpp:2423:77: error: conversion to ‘long unsigned int’ from ‘int’ may change the sign of the result [-Werror=sign-conversion]
         return (size_ == 0) ? 0 : ((size_ - 1) * 8U) + (last_byte_bit_fill_ + 1);
                                                        ~~~~~~~~~~~~~~~~~~~~~^~~~