Tables: fixed seemingly unnecessarily copy of ImGuiTableColumnFlags_NoDirectResize_ which broken resizing from W3| in a F1 W3 F2 setup. Header only allow overlap on hover, not when active (amend f2df804f)
Otherwise TableUpdateBorders() tends to override mouse cursor.
// - F1 F2 F3 resize from F3| --> ok: alter ->WidthRequested of Fixed column. If active, ScrollX extent can be altered.
// - F1 F2 W3 resize from F1| or F2| --> ok: alter ->WidthRequested of Fixed column. If active, ScrollX extent can be altered, but it doesn't make much sense as the Stretch column will always be minimal size.
// - F1 F2 W3 resize from W3| --> ok: no-op (disabled by Resize Rule 1)
// - W1 W2 W3 resize from W1| or W2| --> FIXME
// - W1 W2 W3 resize from W1| or W2| --> ok
// - W1 W2 W3 resize from W3| --> ok: no-op (disabled by Resize Rule 1)
// - W1 F2 F3 resize from F3| --> ok: no-op (disabled by Resize Rule 1)
// - W1 F2 resize from F2| --> ok: no-op (disabled by Resize Rule 1)
// - W1 W2 F3 resize from W1| or W2| --> ok
// - W1 F2 W3 resize from W1| or F2| --> FIXME
// - F1 W2 F3 resize from W2| --> ok
// - F1 W3 F2 resize from W3| --> ok
// - W1 F2 F3 resize from W1| --> ok: equivalent to resizing |F2. F3 will not move. (forwarded by Resize Rule 2)
// - W1 F2 F3 resize from F2| --> FIXME should resize F2, F3 and not have effect on W1 (Stretch columns are _before_ the Fixed column).
// - W1 F2 F3 resize from F2| --> ok
// All resizes from a Wx columns are locking other columns.
// Rules:
// - [Resize Rule 1] Can't resize from right of right-most visible column if there is any Stretch column. Implemented in TableUpdateLayout().