feat: adding the ability to pass a function to terminateVisibilityTimeout

[nicholasgriffintn]

Description:

This adds the ability to pass a function to terminateVisabilityTImeout, which allows you to do exponential backoff based on parameters in the messages (this is always an array even if you don't use batches).

Props to the Vercel fork of SQS Consumer where I noticed and grabbed this from: vercel#1, makes a whole ton of sense.

Type of change:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[github-actions]

LCOV of commit 6a1c8e0 during Comment PR Coverage #91

Summary coverage rate:
  lines......: 97.1% (893 of 920 lines)
  functions..: 100.0% (34 of 34 functions)
  branches...: 94.3% (166 of 176 branches)

Files changed coverage rate:
                   |Lines       |Functions  |Branches    
  Filename         |Rate     Num|Rate    Num|Rate     Num
  =======================================================
  src/consumer.ts  |96.4%    660| 100%    21|93.9%    132