v: forbid local variable names, shadowing imported module names

[ChAoSUnItY]

• Fix Forbid local variables with same name as one of the imported modules #17173, forbids variable name shadowing import symbol.
• Add output test
  var_decl_import_sym_conflict.vv

import arrays

fn x() {
	arrays := 1
}

var_decl_import_sym_conflict.vv:4:2: error: duplicate of an import symbol `arrays`
    2 |
    3 | fn x() {
    4 |     arrays := 1
      |     ~~~~~~
    5 | }

Note

This is a breaking change, serveral modules and tests are effected. Including vinix, stdlib etc.

[spytheman]

Good work.