Adding TCP Info logging support to header rewrite

[dbhat]

This change to the header rewrite plugin allows TCP Info logs to be written out as part of the header.

[vmamidi]

@dbhat Can you also update the documentation?

[masaori335]

[approve ci]
[add to whitelist]

[maskit]

It may be nice to have a subsection about TXN_CLOSE_HOOK under Hook Conditions section on the documentation. If I understand correctly, the hook is special because it's too late to modify/add response headers that will be sent to a client and it only makes sense if you add internal headers.

[dbhat]

@maskit: Added to documentation in commit

[maskit]

Rerunning autest. At minimum tests for header_rewrite pass on my MBP.

[approve ci autest]

[bryancall]

I will review this.