Add necessary safe headers under CORS

[harshavardhana]

Description

Add necessary safe headers under CORS

Motivation and Context

Fixes #5748

How Has This Been Tested?

Manually

Types of changes

• 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)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added unit tests to cover my changes.
• I have added/updated functional tests in mint. (If yes, add mint PR # here: )
• All new and existing tests passed.

[codecov]

Codecov Report

Merging #5750 into master will increase coverage by 1.44%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #5750      +/-   ##
==========================================
+ Coverage   59.11%   60.56%   +1.44%     
==========================================
  Files         193      196       +3     
  Lines       23035    29125    +6090     
==========================================
+ Hits        13618    17639    +4021     
- Misses       7905     9983    +2078     
+ Partials     1512     1503       -9

Impacted Files	Coverage Δ
cmd/generic-handlers.go	77.39% <100%> (-2.24%)	⬇️
cmd/gateway-main.go	18.12% <0%> (-7.41%)	⬇️
cmd/storage-rpc-server.go	75.93% <0%> (-6.92%)	⬇️
cmd/admin-rpc-server.go	35.55% <0%> (-6.34%)	⬇️
cmd/storage-rpc-client.go	78.43% <0%> (-6.23%)	⬇️
cmd/service.go	21.42% <0%> (-5.85%)	⬇️
cmd/server-rlimit.go	54.16% <0%> (-5.84%)	⬇️
cmd/lock-rpc-server.go	47.02% <0%> (-5.68%)	⬇️
cmd/disk-cache-config.go	62.5% <0%> (-5.5%)	⬇️
cmd/format-fs.go	52.7% <0%> (-5.25%)	⬇️
... and 113 more

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[balamurugana]

Mint Automation

Test	Result
mint-xl.sh	✔️
mint-fs.sh	✔️
mint-dist-xl.sh	✔️
mint-gateway-s3.sh	✔️
mint-gateway-azure.sh	✔️

[kannappanr]

LGTM