Code clean up with declare strict and php stan level 9 checks

add "declare(strict_types=1);" to all pages

Add a json handler class to handle that json_decode always returns array<mixed> and throws error otherwise
On failure these will throw the normal JSON encoded error was FAILURE with code "J-" and the number is the json error
If 0 then the return was null or some other problem that did not return an array

amount is float and not string and checks are done that the returned value is a float

various updates for phpdoc array delcarations
- curl header is array<int, string>
- the log array is proper declared as array with string key and a list of mixed arrays

.phan/config.php

@@ -26,6 +26,7 @@
 // use Phan\Config;
 
 return [
+    "minimum_target_php_version" => "7.4",
     // If true, missing properties will be created when
     // they are first seen. If false, we'll report an
     // error message.
@@ -65,7 +66,7 @@ return [
     'directory_list' => [
         // Change this to include the folders you wish to analyze
         // (and the folders of their dependencies)
-        '.'
+        'src/'
         // 'www',
         // To speed up analysis, we recommend going back later and
         // limiting this to only the vendor/ subdirectories your