Strategies for the send protocol

Description

This builds on top of the previous block-per-block exchange protocol by taking a list of blocks and allowing the choice of which peer to send each block to based on a strategy.

We implement two strategies on the trait, which are Random and Round-Robin.

tests/help_func/execute_all_tests.nu

-let error_list = (ls tests/*.nu | where type == file) | each { |test|
+let all_tests = (ls tests/*.nu | where type == file)
+let total_number_of_tests = $all_tests | length 
+let error_list =  $all_tests | each { |test|
     let test_name =  ($test | get name)
     print $"\n(ansi yellow_reverse)    LAUNCHING TEST ($test_name)(ansi reset)\n"
 
@@ -14,6 +16,8 @@ let error_list = (ls tests/*.nu | where type == file) | each { |test|
         
 } | compact
 
+print $"Total number of tests: ($total_number_of_tests)"
+
 if not ($error_list | is-empty) {
     print $"(ansi red_reverse)    ONE OR MORE TESTS FAILED(ansi reset)\n"
     print $error_list