auth: Customize simpleTokenTTL settings.

[cfc4n]

auth: Customize simpleTokenTTL settings.

simple Token TTL default value is auth.simpleTokenTTL = 5 * time.Minute.

Sometimes, this value is not sufficient for use, I hope it can be given to the user to customize the setting.

Fixes #11978

[codecov-commenter]

Codecov Report

Merging #11979 into master will increase coverage by 0.06%.
The diff coverage is 88.23%.

@@            Coverage Diff             @@
##           master   #11979      +/-   ##
==========================================
+ Coverage   65.53%   65.59%   +0.06%     
==========================================
  Files         403      403              
  Lines       37306    37313       +7     
==========================================
+ Hits        24447    24474      +27     
+ Misses      11333    11300      -33     
- Partials     1526     1539      +13     

Impacted Files	Coverage Δ
etcdserver/config.go	79.51% <ø> (ø)
etcdserver/server.go	75.43% <ø> (-0.31%)	⬇️
auth/simple_token.go	67.47% <80.00%> (-9.84%)	⬇️
auth/store.go	53.37% <100.00%> (+0.42%)	⬆️
embed/config.go	54.26% <100.00%> (+0.13%)	⬆️
embed/etcd.go	74.54% <100.00%> (+0.05%)	⬆️
etcdmain/config.go	84.14% <100.00%> (+0.07%)	⬆️
auth/options.go	37.50% <0.00%> (-55.00%)	⬇️
proxy/grpcproxy/register.go	72.50% <0.00%> (-10.00%)	⬇️
... and 28 more

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[cfc4n]

Links: #11980