fdo#71892: sw: fix crash when pasting table in footnote

The code that updates RSIDs assumes that the number of nodes copied is
the same as the number of nodes inserted, which is not true when pasting
a table into a footnote because Writer can't do that, hence all table
nodes are missing.  Count inserted nodes instead.

(regression from 062eaeffe7cb986255063bb9b0a5f3fb3fc8e34c)

Change-Id: I77b5b7751d1036a6401f708532537d874969502e
fdo#71866: sw: un-break index updates

SwTOXBaseSection::GenerateText() wants to operate directly on
SwTxtNode::m_Text and accepts no substitutes such as a temporary string
on the stack; this regression shows that developers often
significantly underestimate the craziness of the existing code.

(regression from d6e321f8264188ce8371c060ebeb75b213f0c90f)

Change-Id: I01b831f35a52bde207a7db8cae9d4aadb826b2d8