[core] Add High as a new warning level

Maps to /W4 on VS and -Wall for gcc/clang removing -Wextra

src/_premake_init.lua

@@ -1250,6 +1250,7 @@
 		allowed = {
 			"Off",
 			"Default",
+			"High",
 			"Extra",
 		}
 	}

src/tools/gcc.lua

@@ -78,6 +78,7 @@
 		},
 		warnings = {
 			Extra = "-Wall -Wextra",
+			High = "-Wall",
 			Off = "-w",
 		},
 		symbols = {

src/tools/msc.lua

@@ -84,6 +84,7 @@
 		},
 		warnings = {
 			Extra = "/W4",
+			High = "/W4",
 			Off = "/W0",
 		},
 		stringpooling = {

tests/tools/test_gcc.lua

@@ -80,6 +80,12 @@
 		test.contains({ "-Wall -Wextra" }, gcc.getcflags(cfg))
 	end
 
+	function suite.cflags_onHighWarnings()
+		warnings "high"
+		prepare()
+		test.contains({ "-Wall" }, gcc.getcflags(cfg))
+	end
+
 	function suite.cflags_onFatalWarnings()
 		flags { "FatalWarnings" }
 		prepare()

tests/tools/test_msc.lua

@@ -181,6 +181,12 @@
 		test.contains("/W0", msc.getcflags(cfg))
 	end
 
+	function suite.cflags_OnHighWarnings()
+		warnings "High"
+		prepare()
+		test.contains("/W4", msc.getcflags(cfg))
+	end
+
 	function suite.cflags_OnExtraWarnings()
 		warnings "Extra"
 		prepare()