replacement for fastled sqrt16() (#4426)

* added bitwise operation based sqrt16

- replacement for fastled, it is about 10% slower for numbers smaller 128 but faster for larger numbers. speed difference is irrelevant to WLED but it saves some flash.

* updated to 32bit, improved for typical WLED use

- making it 32bits allows for larger numbers
- added another initial condition check for medium sized numbers
- increased the "small number" optimization to larger numbers: the function is currently only used to calculate sqrt(x^2+y^2) which even for small segments is larger than the initially used 64, so optimizing for 1024 makes more sense, although the value is arbitrarily chosen

wled00/FX_fcn.cpp

@@ -932,7 +932,7 @@ uint16_t Segment::calc_virtualLength() const {
         break;
       case M12_pArc:
         { unsigned vLen2 = vW * vW + vH * vH;            // length ^2
-          if (vLen2 < UINT16_MAX) vLen = sqrt16(vLen2);  // use faster function for 16bit values
+          if (vLen2 < UINT16_MAX) vLen = sqrt32_bw(vLen2);  // use faster function for 16bit values
           else vLen = sqrtf(vLen2);                      // fall-back to float if bigger
           if (vW != vH) vLen++; // round up
         }