The original intent of #12056 was to improve parsing recovery in the
cast of a leading accessibility modifier on a local function. However, I
mistakenly allowed for recovery for an accessibility modifier *anywhere*
in the modifier list of the local function.

This is a mistake because it significantly complicates parsing back-out.
While it's easy to recognize that the local function parsing failed and
skip any leading accessibility modifiers, it's significantly more
complicated to find and skip all accessibility modifiers anywhere in a
sequence of modifiers.

This PR changes the parsing backout to only consider accessibility
modifiers at the start of statements. Any other case will be treated
like other bad modifiers in local functions -- they will be marked as
errors in the declaration list. Fixes #12947.

Entered tracking bugs instead as customary when merging into Master branch.

Related to #12597.

Although I have been able to get the IDE to crash before this change, I don't have a simple repro.