feat(core): update default pattern

[aquariuslt]

update default pattern to %[[%d{yyyy-MM-dd hh:mm:ss:SSS}][%z][%p][%X{name}]%] - %m%n

Closes #253

[codecov]

Codecov Report

Merging #255 into master will increase coverage by 2.16%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #255      +/-   ##
==========================================
+ Coverage   85.10%   87.27%   +2.16%     
==========================================
  Files           5        5              
  Lines          47       55       +8     
  Branches        6        7       +1     
==========================================
+ Hits           40       48       +8     
  Misses          4        4              
  Partials        3        3              

Flag	Coverage Δ
#unittests	87.27% <100.00%> (+2.16%)	⬆️

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Impacted Files	Coverage Δ
packages/core/src/log4js.options.ts	84.61% <ø> (ø)
packages/core/src/log4js.classes.ts	100.00% <100.00%> (ø)

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