添加数据字典功能

[kjiLupin]

关联pr #264 #265

• 增加MySQL数据字典功能
• 实时查询实例元数据，支持通过表头索引定位表
• 展示表status、column、index、create table 信息

[codecov]

Codecov Report

Merging #266 into feature/mysql_data_dictionary will increase coverage by 0.15%.
The diff coverage is 70.39%.

@@                        Coverage Diff                        @@
##           feature/mysql_data_dictionary     #266      +/-   ##
=================================================================
+ Coverage                           83.2%   83.35%   +0.15%     
=================================================================
  Files                                 65       66       +1     
  Lines                               8252     8472     +220     
=================================================================
+ Hits                                6866     7062     +196     
- Misses                              1386     1410      +24

Impacted Files	Coverage Δ
sql/engines/mysql.py	91.16% <ø> (ø)	⬆️
sql/completer/mysql.py	100% <ø> (ø)	⬆️
sql/utils/tests.py	98.88% <100%> (+0.04%)	⬆️
sql/engines/tests.py	99.76% <100%> (ø)	⬆️
sql/engines/goinception.py	91.3% <100%> (ø)	⬆️
sql/urls.py	100% <100%> (ø)	⬆️
sql/utils/sql_review.py	97.18% <100%> (+0.46%)	⬆️
sql/models.py	94.92% <100%> (+0.02%)	⬆️
sql/tests.py	95.52% <100%> (+0.4%)	⬆️
sql/data_dictionary.py	17.54% <17.54%> (ø)
... and 10 more

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[hhyo]

新建了一个分支来合并，准备写入到engine的方法中，并且完善测试