parser,checker: add new array syntax support

[kbkpbot]

Feature requested by #25183

NOTE: vfmt need further fix to work with new array syntax, in anther PR.

new.v

module main

const kkk = 20

fn main() {
        // old syntax
        o1 := []int{}
        dump(o1)
        o2 := [int(1),2,3,4]
        dump(o2)
        o3 := [kkk]int{}
        dump(o3)
        o4 := [int(1),2,3,4]!
        dump(o4)

        // new syntax
        n1 := []int[1 2 3 4]
        dump(n1)
        n2 := [4]int[1 2 3 4]
        dump(n2)
        n3 := [..]int[1 2 3 4]
        dump(n3)
        /*
        // not work yet
        n4 := [4][4]f32[
                 [1 2 3 4]
                 [5 5 4 2]
                 [0 1 3 0]
                 [0 1 4 1]
        ]
        dump(n4)
        n5 := [..][..]f32[
                 [1 2 3 4]
                 [5 5 4 2]
                 [0 1 3 0]
                 [0 1 4 1]
        ]
        dump(n5)
        */
}

[kbkpbot]

autofree has some bug, need to fix in another PR.
Issue #25366

[spytheman]

You can use this as a workaround for the autofree compilation:

41|  |-    pre_cmnts = p.eat_comments()
  |41|+    pre_cmnts.clear()
  |42|+    pre_cmnts << p.eat_comments()