Upgrade go version to 1.18

[niladrih]

Signed-off-by: Niladri Halder niladri.halder26@gmail.com

What type of PR is this?
/kind enhancement

What this PR does / why we need it:
This PR upgrades the go version to 1.18 from 1.12. This removes the vendor directory.

Which issue(s) this PR fixes:
Fixes #1323

Test Report Added?:
/kind NOT-TESTED

Test Report:
N/A

Special notes for your reviewer:
#SODACODE2022

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 39.13%. Comparing base (a689e17) to head (2dec741).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1324      +/-   ##
==========================================
+ Coverage   38.93%   39.13%   +0.20%     
==========================================
  Files          53       53              
  Lines        6966     9615    +2649     
==========================================
+ Hits         2712     3763    +1051     
- Misses       3739     5337    +1598     
  Partials      515      515              

Files with missing lines	Coverage Δ
pkg/db/drivers/etcd/client.go	0.00% <ø> (ø)

... and 52 files with indirect coverage changes

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[sushanthakumar]

@himanshuvar @PravinRanjan10 , pls have a look

[sushanthakumar]

#SODACODE-PR-ACCEPTED
This PR is accepted for SODACODE 2022. But merge will be done after appropriate testing as it involves many file changes.
Thanks @niladrih for the contribution