fix(inject): Make pragma detection stricter

[loewenheim]

We only want to skip "actual" use pragmas and not those that are contained in some function object. Therefore we anchor the pragma regex to the start of the line.

[kamilogorek]

There are still some nasty cases like

"use strict"; // this is a multi-line
// banner comment
// that describes author, license, version etc.

which will end up as

"use strict"; // this is a multi-line
<our-snippet>
// banner comment
// that describes author, license, version etc.

But I dont think that it's a real problem here tbh. It will function just fine.