kernel: Make >>#new/>>#new: go through >>#initialize

In Pharo it is common that new/new: will already go through an
initialize call. When porting code from and to Pharo one needs
to make sure that initialize is called and only called once or
idempotent. Align the code with Pharo.
misc: Remove redundant >>#new implementations

Remove implementations that used to call super new/self basicNew
followed by a call to initialize. Remove empty >>#initialize selectors