fix(parser): reject await in the concise body of a non-async arrow in module code - #673

In module code, meriyah accepted await used as an expression in the concise body of a non-async arrow function:

// sourceType: 'module'
x => await x;
f(b => await + x);
`${b => await b}`;

An arrow's concise body is ConciseBody[~Await] for non-async arrows, so await there is neither an AwaitExpression nor (in module code) a valid identifier — these are early errors. acorn rejects all three. The block-body form (x => { await x }) was already rejected, because the function body parser clears Context.InGlobal; the concise-body path kept it, so top-level-await handling leaked into the arrow.

The fix adds Context.InGlobal to the flags cleared in parseArrowFunctionExpression, so both body forms behave the same.

Tests: three new fail cases in test/parser/expressions/arrow.ts (they pass parsing without the fix). The full suite (92,032 tests, rebased on main) and npm run lint pass.