Mixed keyed and unkeyed elements in a slice are not supported

[piux2]

Description

Mixed keyed and unkeyed elements in a slice should be allowed.

According to the go specs https://go.dev/ref/spec

For array and slice literals the following rules apply:
- Each element has an associated integer index marking its position in the array.
- An element without a key uses the previous element's index plus one. If the first element has no key, its index is zero.

Your environment

• Go version (example: go1.22)
• OS and CPU architecture (MacOS/ARM64)
• Gno commit hash causing the issue (6472eea)

Steps to reproduce

// slice4.gno
package main

func main() {
	var x = []int{4: 14, 25, 1: 33, 34}
	println(len(x), x[2])
}

// Output:
//  6 34

• add above file to gnovm/tests/files/slice/slice4.gno
• go test gnovm/pkg/gnolang/files_test.go -run 'TestFiles/slice/'

Expected behaviour

It should pass, and the output should be 6 34

https://go.dev/play/p/QWy6BXtDJZV?v=goprev

Actual behaviour

--- FAIL: TestFiles (0.04s)
--- FAIL: TestFiles/slice/slice4.gno (0.00s)
panic: slice composite literal cannot mix keyed and unkeyed elements [recovered]
panic: slice composite literal cannot mix keyed and unkeyed elements [recovered]
panic: interface conversion: gnolang.Stmt is *gnolang.ValueDecl, not *gnolang.bodyStmt [recovered]
panic: interface conversion: gnolang.Stmt is *gnolang.ValueDecl, not *gnolang.bodyStmt