Improve bodyWrapper Rewind test

[gavv]

bodyWrapper is an internal struct that wraps HTTP response body and allows to read it multiple times using Rewind and GetBody methods. See comments for details.

Currently TestBodyWrapper_Rewind has two subtests:

• "readall - close - rewind - readall"
• "rewind - readall - close - rewind - readall"

Subtest name describes the order of performed operations.

It would be nice to cover a few more combinations of operations:

• "readall - rewind - readall" (no close before rewind)
• "close - rewind - readall" (no readall before rewind)
• "rewind - readall - rewind - readall" (no close after rewind)
• "rewind - close - rewind - readall" (no readall after rewind)
• "loop" ("readall - close - rewind" repeated a few times)

[AnandaIlyasa]

hi @gavv i'd like to work on this

[gavv]

@AnandaIlyasa Welcome, thanks!

[gavv]

Merged via 8d90e3b, thanks!