Initial port to mozjs102

Todos:

• Don't use 0 (and 1) as magic values for reserved slots (I'm using 0 for private values now)

Notes:

• I used 103a1 with this commit because a esr102 branch/tag doesn't exist yet
• I had to copy a mozglue-related header from esr91 to make the build functional (ProfilingCategoryList.h)

Relevant changes:

• JS::SetPrivate/JS::GetPrivate have been removed (https://bugzilla.mozilla.org/show_bug.cgi?id=1722453, https://phabricator.services.mozilla.com/D120940)
• JS_ID_* APIs have been removed (https://bugzilla.mozilla.org/show_bug.cgi?id=1754405)
  • SYMBOL_TO_ID https://hg.mozilla.org/mozilla-central/rev/75e45f7f6059a982dab85a070d6becbbfb699e92
  • JS_ID_TO_LINEAR_STRING https://hg.mozilla.org/mozilla-central/rev/e4f4811ae8ff6b0a4e1b8e016f2ba7b98cfd3800
• Pinning JSStrings has been removed (https://bugzilla.mozilla.org/show_bug.cgi?id=1724234, https://hg.mozilla.org/mozilla-central/rev/69391950f9a2bc047c1371fad4fb94899c88baa3)
• Creating ArrayObject with an empty handle array causes a segfault now??
  • JS::RootedObject array(context, JS::NewArrayObject(context, JS::HandleValueArray::empty()))
• CloneAndExecuteScript was removed (https://bugzilla.mozilla.org/show_bug.cgi?id=1718529, https://hg.mozilla.org/mozilla-central/rev/506b2659c7f96f732935a55282a6fa132705c7f6)
• SafelyInitialized no longer has a constructor (https://hg.mozilla.org/mozilla-central/rev/551bd2292b5c9722f77f4501191a32a605a9f89b)