Support for KDF counter and feedback modes with HMAC

[lealem47]

Description

Adds wc_HMAC_KDF_Counter() and wc_HMAC_KDF_Feedback() APIs enabled by defining HAVE_HMAC_PRF_KDF.
From feature request list.

Testing

Vectors from NIST in wolfCrypt test.

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation

[dgarske]

Looks good to me, but haven't tested. @SparkiDev will you please review and provide feedback?

[SparkiDev]

I'm seeing these different KDFs:

1. mode == 1 (HMAC_KDF_FEEDBACK_MODE)
   IV or key | info
2. mode == 0 (HMAC_KDF_CTR_MODE), ctrLocation = BEFORE_FIXED
   Counter | Info
3. mode == 0 (HMAC_KDF_CTR_MODE), ctrLocation = AFTER_FIXED
   Info | Counter
4. mode == 0 (HMAC_KDF_CTR_MODE), ctrLocation = MIDDLE_FIXED
   info | Counter | remainingInfo

I don't see n changing in the loop.

The underlying common operation is HMAC of 2 or three items.
Make the hidden API take three items which are all optional - NULL means don't hash.
Then, depending on mode and ctrLocation, pass different buffers in for the different items to be hashed.
One is sometimes a counter which needs to be updated based on a parameter to the hidden function.

[SparkiDev]

2^n -1 == (1 << n) - 1