feat: add retry informational headers

[trivikr]

Issue #, if available:
Internal issue in JS-1816

Description of changes:
add retry informational headers

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[codecov-commenter]

Codecov Report

Merging #1266 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1266      +/-   ##
==========================================
+ Coverage   73.04%   73.06%   +0.01%     
==========================================
  Files         287      287              
  Lines       12730    12737       +7     
  Branches     2922     2924       +2     
==========================================
+ Hits         9299     9306       +7     
  Misses       3431     3431              

Impacted Files	Coverage Δ
packages/middleware-retry/src/defaultStrategy.ts	100.00% <100.00%> (ø)

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[AllanZhengYP]

Looks good to me. For future record: ttl from amz-sdk-request header is omitted from this PR.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs and link to relevant comments in this thread.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs and link to relevant comments in this thread.