Fix: truncation of text array and sequences by NULL terminator

Fix: truncation of text array and sequences by NULL terminator

The recent refactor does not take into account that text array and text
sequence types behave like Pascal Strings and not C strings, which means
the NULL terminator is optional, and the string size is delimited by the
array or sequence length.

Introduce a new lib_ring_buffer_pstrcpy() to handle copying into a ring
buffer Pascal String, and use it for array and sequence of text.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: 2792781482a5 ("ABI refactoring: sequence and array of text: copy input as string")
Fixes: #1301
Change-Id: Idcc13f061d5229496476f42dce84c2f395b7f6e6