K2: Fix false-positive resolution to j.l.String constructor

In K1 (see LazyImportScope), default start import with different
priority worked as follows:
- if something is found in HIGH, don't look at LOW
- otherwise, look at LOW

That, in particular, helped to avoid looking into JDK mirroring classes'
constructors like when resolving calls like String(...) because we
just don't look into j.l.String while already found kotlin.String

The change inside FirTowerResolveTask.kt is not made accidentally:
- At first, it's more or less obviously a bug fix because tower group
for hide-members candidate with implicit receiver should take into
account the tower level of the receiver itself.
- The change is attached to this commit because otherwise the test
at compiler/testData/diagnostics/testsWithStdLib/kt55503.kt starts
failing.
The bug was hidden because previously after finding a successful
`Sequence.forEach` candidate for the inner receiver
(at the default HIGH star import scope), resolver was continuing to
look into default LOW star import scope where it's frozen forever because
we had the better/closer candidate anyway.

But after this change with merging default star imports into the same
tower leve, resolver was continuing its job, enumerating implicit
receivers, finding List<Int> there and noticing that there's
a TopPrioritized hide-member candidates for them
(erroneously ignoring it has a worse/more far receiver).

^KT-51670 Fixed

compiler/fir/analysis-tests/testData/resolveWithStdlib/problems/stringConstructors.kt

@@ -2,10 +2,7 @@
 
 val sRef = ::String
 
-// Note: FE 1.0 resolves this to kotlin.text.String() synthetic call with type mismatch on the last argument
-// May be we (FIR) should migrate to the same behavior
-// Other properties in this file are resolved similarly in FE 1.0 & FIR
-val s = <!DEPRECATION!>String<!>(byteArrayOf(1, 2, 3), 4, 5, 6)
+val s = String(byteArrayOf(1, 2, 3), 4, 5, <!ARGUMENT_TYPE_MISMATCH!>6<!>)
 
 val s2 = java.lang.<!DEPRECATION!>String<!>(byteArrayOf(1, 2, 3), 4, 5, 6)
 val s3 = String(byteArrayOf(1, 2, 3), 4, 5)