Merge adjacent sibling templates in a fragment into one template

[ryansolid]

Moved from ryansolid/dom-expressions#458.

A fragment of adjacent static siblings compiles to one template() per root:

<>
  <div />
  <button type="button">hi</button>
</>

var _tmpl$ = _$template(`<div>`),
  _tmpl$2 = _$template(`<button type=button>hi`);

Those could be a single template string (and one clone) when nothing dynamic sits between them. Reported by @milomg; playground: https://playground.solidjs.com/anonymous/6f9638af-453b-4841-b8cd-76ea1c4fc15a