Adjust phan to allow for making progress strengthening analysis

With phan set to only report critical errors it will be quite hard
to cleanup the code base to the point where we are running stronger
analysis. Instead of setting minimimum severity to critical, set
minimum severity to low and suppress all existing issues.

This will allow developers to choose an issue type from the list, fix
it, and update the config.php to report on the issue in the future.

Change-Id: I2771a4ff37f43cca215b939ed7d82f137d72cea6

tests/phan/config.php

@@ -95,6 +95,8 @@
 		'maintenance/language/',
 		// External class
 		'includes/libs/jsminplus.php',
+		// separate repositories
+		'skins/'
 	],
 
 	/**
@@ -165,8 +167,10 @@
 	 */
 	'analyze_signature_compatibility' => true,
 
-	// Only emit critical issues
-	"minimum_severity" => 10,
+	// Emit all issues. They are then supressed via
+	// suppress_issue_types, rather than a minimum
+	// severity.
+	"minimum_severity" => 0,
 
 	/**
 	 * If true, missing properties will be created when
@@ -289,14 +293,72 @@
 	 * to this black-list to inhibit them from being reported.
 	 */
 	'suppress_issue_types' => [
-		// MediaWiki has so much deprecated class usage it's a bit hopeless to
-		// fix this immediately
-		'PhanDeprecatedClass',
-		'PhanDeprecatedFunction',
-		'PhanDeprecatedProperty',
-		// There are arround 1400 usages of undeclared properties.
-		// php is ok with that but it's a code smell.
-		'PhanUndeclaredProperty',
+		// approximate error count: 8
+		"PhanDeprecatedClass",
+		// approximate error count: 441
+		"PhanDeprecatedFunction",
+		// approximate error count: 24
+		"PhanDeprecatedProperty",
+		// approximate error count: 12
+		"PhanParamReqAfterOpt",
+		// approximate error count: 748
+		"PhanParamSignatureMismatch",
+		// approximate error count: 7
+		"PhanParamSignatureMismatchInternal",
+		// approximate error count: 1
+		"PhanParamSpecial1",
+		// approximate error count: 2
+		"PhanParamTooFew",
+		// approximate error count: 308
+		"PhanParamTooMany",
+		// approximate error count: 3
+		"PhanParamTooManyInternal",
+		// approximate error count: 1
+		"PhanRedefineFunction",
+		// approximate error count: 1
+		"PhanRedefineFunctionInternal",
+		// approximate error count: 2
+		"PhanTraitParentReference",
+		// approximate error count: 4
+		"PhanTypeArraySuspicious",
+		// approximate error count: 4
+		"PhanTypeComparisonFromArray",
+		// approximate error count: 1
+		"PhanTypeInvalidLeftOperand",
+		// approximate error count: 3
+		"PhanTypeInvalidRightOperand",
+		// approximate error count: 563
+		"PhanTypeMismatchArgument",
+		// approximate error count: 39
+		"PhanTypeMismatchArgumentInternal",
+		// approximate error count: 4
+		"PhanTypeMismatchDefault",
+		// approximate error count: 16
+		"PhanTypeMismatchForeach",
+		// approximate error count: 63
+		"PhanTypeMismatchProperty",
+		// approximate error count: 95
+		"PhanTypeMismatchReturn",
+		// approximate error count: 16
+		"PhanTypeMissingReturn",
+		// approximate error count: 5
+		"PhanTypeNonVarPassByRef",
+		// approximate error count: 3
+		"PhanTypeVoidAssignment",
+		// approximate error count: 27
+		"PhanUndeclaredConstant",
+		// approximate error count: 185
+		"PhanUndeclaredMethod",
+		// approximate error count: 1342
+		"PhanUndeclaredProperty",
+		// approximate error count: 9
+		"PhanUndeclaredStaticMethod",
+		// approximate error count: 15
+		"PhanUndeclaredTypeParameter",
+		// approximate error count: 1
+		"PhanUndeclaredTypeProperty",
+		// approximate error count: 79
+		"PhanUndeclaredVariable",
 	],
 
 	/**