Pair and Triple Compare w/ Unit Tests (#2359)

* Pair and Triple Compare w/ Unit Tests
* scope creep myself by adding date-time eq op
* make Pair and Triple printable
* Update releasenotes. Restrict equals on tuples to when underlying type supports `==`. Remove unnecessary Time.eq.

---------

Co-authored-by: Christoffer Lerno <christoffer@aegik.com>

test/unit/stdlib/collections/tuple.c3

@@ -0,0 +1,71 @@
+module tuple_test;
+
+struct TestStruct
+{
+    String a;
+    int b;
+}
+
+fn bool TestStruct.eq(self, TestStruct other) @operator(==)
+    => self.a == other.a && self.b == other.b;
+
+
+module tuple_test @test;
+
+import std::collections::pair;
+import std::collections::triple;
+
+
+fn void pair_make_and_unpack()
+{
+    Pair { ulong, String } x = { 0x8034534, "some string" };
+
+    assert(x.first == 0x8034534);
+    assert(x.second == "some string");
+
+    ulong a;
+    String b;
+    x.unpack(&a, &b);
+
+    assert(a == 0x8034534);
+    assert(b == "some string");
+}
+
+fn void pair_compare()
+{
+    Pair { TestStruct, String } x = { {"left", -123}, "right" };
+    Pair { TestStruct, String } y = { {"left", -123}, "right" };
+    Pair { TestStruct, String } z = { {"left", 4096}, "right" };
+
+    assert(x == y);
+    assert(x != z);
+}
+
+fn void triple_make_and_unpack()
+{
+    int myval = 7;
+    Triple { ulong, String, int* } x = { 0xA_DEAD_C0DE, "yet another string", &myval };
+
+    assert(x.first == 0xA_DEAD_C0DE);
+    assert(x.second == "yet another string");
+    assert(x.third == &myval);
+
+    ulong a;
+    String b;
+    int* c;
+    x.unpack(&a, &b, &c);
+
+    assert(a == 0xA_DEAD_C0DE);
+    assert(b == "yet another string");
+    assert(c == &myval);
+}
+
+fn void triple_compare()
+{
+    Triple { TestStruct, String, String } x = { {"in", 42}, "left", "right" };
+    Triple { TestStruct, String, String } y = { {"in", 42}, "left", "right" };
+    Triple { TestStruct, String, String } z = { {"in", 42}, "up", "down" };
+
+    assert(x == y);
+    assert(x != z);
+}