fix(pilota)/use advance method to align the inner buffer index with the protocol index when feasible

[Ggiggle]

Motivation

The inner buffer index might not align with the index of protocol for better performance of vector encoding or decoding. Thus, when we use the buf or buf_mut interface which return the inner buffer, we might encounter the issue of reading or writing at wrong position of the buffer.

Solution

As there are some low frequency option, such as read_message_begin, which are not pursuing performance, we can use the advance and advance_mut method to align the inner buffer index with the index of protocol implement. Then, we can get the right payload after read_message_begin.

As a reminder, this PR cannot completely resolve the inconsistency problem of these two indexes, so be careful of using the buf and buf_mut in the middle of processing the thrift message.