VS,Xcode: Drop incorrect legacy dependency trace (#14291)

Drop the "vsProjectFile" argument from cmTarget::TraceDependencies.  It
appears to be the modern equivalent to a hunk added in commit ba68f771
(...added new custom command support, 2003-06-03):

 +  name = libName;
 +  name += ".dsp.cmake";
 +  srcFilesToProcess.push(name);

but was broken by refactoring at some point.  The current behavior tries
to trace dependencies on a source file named the same as a target, which
makes no sense.  Furthermore, in code of the form

 add_executable(foo foo.c)
 add_custom_command(OUTPUT "${somewhere}/foo" ... DEPENDS foo)

the "vsProjectFile" value "foo" matches source "${somewhere}/foo.rule"
generated to hold the custom command and causes the command to be added
to the "foo" target incorrectly.

Simply drop the incorrect source file trace and supporting logic.
Merge topic 'drop-old-vs-dependency' into next

4bb6e24 VS,Xcode: Drop incorrect legacy dependency trace (#14291)