Move functions from func.d to funcsem.d.

These require `import dscope` that we want to remove from func.d in pursuit of https://github.com/orgs/dlang/projects/41.

Other functions that still need to be moved include `overloadApply()`, `isUnique()` and `equals()`, the latter needing a visitor akin dlang#15782.

compiler/src/dmd/dclass.d

@@ -26,6 +26,7 @@ import dmd.dsymbol;
 import dmd.dsymbolsem;
 import dmd.errors;
 import dmd.func;
+import dmd.funcsem;
 import dmd.id;
 import dmd.identifier;
 import dmd.location;

compiler/src/dmd/declaration.d

@@ -27,6 +27,7 @@ import dmd.dtemplate;
 import dmd.errors;
 import dmd.expression;
 import dmd.func;
+import dmd.funcsem;
 import dmd.globals;
 import dmd.gluelayer;
 import dmd.id;

compiler/src/dmd/dmangle.d

@@ -147,6 +147,7 @@ import dmd.dtemplate;
 import dmd.errors;
 import dmd.expression;
 import dmd.func;
+import dmd.funcsem;
 import dmd.globals;
 import dmd.id;
 import dmd.identifier;

compiler/src/dmd/dstruct.d

@@ -28,6 +28,7 @@ import dmd.dtemplate;
 import dmd.errors;
 import dmd.expression;
 import dmd.func;
+import dmd.funcsem;
 import dmd.globals;
 import dmd.id;
 import dmd.identifier;

compiler/src/dmd/escape.d

@@ -25,6 +25,7 @@ import dmd.dsymbol;
 import dmd.errors;
 import dmd.expression;
 import dmd.func;
+import dmd.funcsem;
 import dmd.globals : FeatureState;
 import dmd.id;
 import dmd.identifier;