Fix `terraform console` crash for ephemeral values (#36267)

We now check if a value has an ephemeral mark before trying to format
it. The check prevents us from passing a marked value to go-cty's
AsString function, which leads to a crash.

internal/repl/format.go

@@ -23,6 +23,9 @@ func FormatValue(v cty.Value, indent int) string {
 	if v.HasMark(marks.Sensitive) {
 		return "(sensitive value)"
 	}
+	if v.HasMark(marks.Ephemeral) {
+		return "(ephemeral value)"
+	}
 	if v.IsNull() {
 		ty := v.Type()
 		switch {

internal/repl/format_test.go

@@ -177,6 +177,10 @@ EOT_`,
 			cty.StringVal("a sensitive value").Mark(marks.Sensitive),
 			"(sensitive value)",
 		},
+		{
+			cty.StringVal("an ephemeral value").Mark(marks.Ephemeral),
+			"(ephemeral value)",
+		},
 	}
 
 	for _, test := range tests {