Dereferencing tags' children in DSL 🔥
**Is your feature request related to a problem? Please describe.** 🤔
Now that `buildHtml` can generate fragments of DSL code, the next natural thing to do with them is to place them in more complex data structures other than simple assignments. Procs returning `TagRefs `and seqs/sets/tables of `TagRefs`  are all valuable, but if simplicity is a priority, then simply having a convenient way to de-reference children would be enough.

Given that components can only have one slot, for example, accessing the children of slot allows components to have a variable number of `TagRef` arguments and post them to the page in more selective and complex ways.

Currently we can access children and assign to a variable, but cannot use `[]` directly to place a `TagRef`:

```

appRoutes("ROOT"):
  "/":
    let myList = buildHtml:
      tDiv: "a"
      tDiv: "b"
      tDiv: "c"
    let myItem = myList.children[2]
    myItem
    # myList.children[2]

```

The code will run and selects `tDiv: "c"`, but the commented code fails. Currently the compiler says it expected an identifier but didn't get one; ideally it seems we want to allow any call that returns a `static string` or a `Component` or a `TagRef`