Don't mess up syntax-ppss cache in electric-pair (Bug#29710)

Don't mess up syntax-ppss cache in electric-pair (Bug#29710)

In Emacs 25 and above, calling `scan-sexps', `parse-partial-sexp', or
similar may update the syntax-ppss cache if
`parse-sexp-lookup-properties' is non-nil.  Therefore, when calling
any of these functions with a different than normal syntax-table, the
cache must be cleaned afterwards.
* lisp/elec-pair.el (electric-pair--with-uncached-syntax): New macro.
(electric-pair--syntax-ppss, electric-pair--balance-info): Use it.