Max elastic exported request/response size

[Mzack9999]

Proposed changes

This PR implements a new flag -max-size to control the maximum length of exported request/response to elastic

Checklist

• Pull request is created against the dev branch
• All checks passed (lint, unit/integration/regression tests etc.) with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[ehsandeep]

@Mzack9999 any advantages of using -elastic-max-field-size over the common flag that will be applicable for all the exports and not specific to elastic?

   -rsts, -response-size-to-save int  max response size to save in bytes (default 2147483647)
   -rstr, -response-size-to-read int  max response size to read in bytes (default 2147483647)

[Mzack9999]

Both flags don't make sense within an http proxy as we need to read and process always the whole requests/responses. I've renamed the flag to max-size under the export section, and now the data saved is always truncated at the maximum size if specified

[tarunKoyalwar]

lgtm !