refactor!: improve xlog with less and robust api

[sysulq]

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[codecov-commenter]

Codecov Report

Merging #321 (4504d44) into master (f38db3d) will decrease coverage by 0.48%.
The diff coverage is 40.27%.

@@            Coverage Diff             @@
##           master     #321      +/-   ##
==========================================
- Coverage   34.10%   33.61%   -0.49%     
==========================================
  Files          88       89       +1     
  Lines        6445     6268     -177     
==========================================
- Hits         2198     2107      -91     
+ Misses       4114     4034      -80     
+ Partials      133      127       -6     

Impacted Files	Coverage Δ
pkg/client/rocketmq/init.go	1.78% <0.00%> (ø)
pkg/client/rocketmq/option.go	71.08% <0.00%> (ø)
pkg/client/rocketmq/producer.go	44.71% <0.00%> (ø)
pkg/conf/datasource/apollo/register.go	3.33% <0.00%> (ø)
pkg/executor/xxl/options.go	93.24% <0.00%> (ø)
pkg/store/gorm/config.go	0.00% <0.00%> (ø)
pkg/store/gorm/init.go	30.76% <ø> (-11.54%)	⬇️
pkg/util/xgo/init.go	10.00% <ø> (ø)
pkg/xlog/context.go	56.52% <0.00%> (ø)
pkg/xlog/field.go	0.00% <ø> (ø)
... and 15 more

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