[FIR] Add CLI flag for running extended checkers

compiler/testData/cli/js/jsExtraHelp.out

@@ -70,6 +70,7 @@ where advanced options include:
   -Xskip-prerelease-check    Allow to load pre-release classes
   -Xuse-experimental=<fq.name> Enable, but don't propagate usages of experimental API for marker annotation with the given fully qualified name
   -Xuse-fir                  Compile using Front-end IR. Warning: this feature is far from being production-ready
+  -Xuse-fir-extended-checkers Use extended analysis mode based on Front-end IR. Warning: this feature is far from being production-ready
   -Xuse-mixed-named-arguments Enable Support named arguments in their own position even if the result appears as mixed
   -Xverbose-phases           Be verbose while performing these backend phases
 

compiler/testData/cli/jvm/extendedCheckers.args

@@ -0,0 +1,5 @@
+$TESTDATA_DIR$/extendedCheckers.kt
+-Xuse-fir
+-Xuse-fir-extended-checkers
+-d
+$TEMP_DIR$

compiler/testData/cli/jvm/extendedCheckers.kt

@@ -0,0 +1,3 @@
+fun foo() {
+    val i: Int = 1
+}

compiler/testData/cli/jvm/extendedCheckers.out

@@ -0,0 +1,4 @@
+compiler/testData/cli/jvm/extendedCheckers.kt:2:12: warning: redundant explicit type
+    val i: Int = 1
+           ^
+OK

compiler/testData/cli/jvm/extendedCheckersNoWarning.args

@@ -0,0 +1,5 @@
+$TESTDATA_DIR$/extendedCheckersNoWarning.kt
+-Xuse-fir
+-Xuse-fir-extended-checkers
+-d
+$TEMP_DIR$

compiler/testData/cli/jvm/extendedCheckersNoWarning.kt

@@ -0,0 +1,3 @@
+fun foo() {
+    val s = "Say 'Hi!' to extended checkers"
+}

compiler/testData/cli/jvm/extendedCheckersNoWarning.out

@@ -0,0 +1 @@
+OK

compiler/testData/cli/jvm/extraHelp.out

@@ -153,6 +153,7 @@ where advanced options include:
   -Xskip-prerelease-check    Allow to load pre-release classes
   -Xuse-experimental=<fq.name> Enable, but don't propagate usages of experimental API for marker annotation with the given fully qualified name
   -Xuse-fir                  Compile using Front-end IR. Warning: this feature is far from being production-ready
+  -Xuse-fir-extended-checkers Use extended analysis mode based on Front-end IR. Warning: this feature is far from being production-ready
   -Xuse-mixed-named-arguments Enable Support named arguments in their own position even if the result appears as mixed
   -Xverbose-phases           Be verbose while performing these backend phases