fix importName for multi-import in single file

[nighca]

In goplus/igop#275, we use spx@patch to enable generic types in igop. The expected output for an spx project is:

package main

import (
	"github.com/goplus/spx"
	spx1 "github.com/goplus/spx@patch"
)

func (this *Game) MainEntry() {
	// ...
	spx1.Gopt_Game_Gopx_GetWidget[spx.Monitor](this, "monitor")
	// ...
}

However, after #445, the spx project is compiled to:

import (
	"github.com/goplus/spx"
	"github.com/goplus/spx@patch"
)

func (this *Game) MainEntry() {
	// ...
	spx.Gopt_Game_Gopx_GetWidget[spx.Monitor](this, "monitor")
	// ...
}

That leads to an error when running the compiled code:

Failed to run Go+ source: main.go:5:2: spx redeclared in this block  Code: 2

This PR addresses the issue by implementing import-name coordination within file.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.93%. Comparing base (dc8cddf) to head (e195189).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #466   +/-   ##
=======================================
  Coverage   95.93%   95.93%           
=======================================
  Files          18       18           
  Lines        7184     7191    +7     
=======================================
+ Hits         6892     6899    +7     
  Misses        228      228           
  Partials       64       64           

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[nighca]

@visualfc @xushiwei Plz review.