Do not search icu when boost is found system wide
Add cmake variables for tests, wallet and bench options
Signed-off-by: Anthony Fieroni <bvbfan@abv.bg>
This contains significant rebase / merge / testing work by Naut
<lbrynaut@protonmail.com>, Anthony Fieroni <bvbfan@abv.bg> and Brannon
King <countprimes@gmail.com>.