Remove redundant DB access for ACL

[zhugelianglongming]

1. Remove redundant DB access for ACL
2. Improve performance
3. Improve readability
4. Refactor code style: Procedural-Oriented -> Object-Oriented
5. Improve code coverage

Fix #435

[codecov-commenter]

Codecov Report

Merging #441 (719cb03) into master (af39eb9) will increase coverage by 0.27%. The diff coverage is 82.29%.

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@@            Coverage Diff             @@
##           master     #441      +/-   ##
==========================================
+ Coverage   45.06%   45.34%   +0.27%     
==========================================
  Files         145      151       +6     
  Lines       12996    13205     +209     
==========================================
+ Hits         5857     5988     +131     
- Misses       5955     6026      +71     
- Partials     1184     1191       +7     

Impacted Files	Coverage Δ
kernel/permission/acl/utils/def.go	16.66% <0.00%> (ø)
kernel/permission/acl/acl.go	63.15% <63.15%> (ø)
kernel/permission/acl/contract.go	91.20% <93.75%> (ø)
kernel/permission/acl/bucket/account.go	100.00% <100.00%> (ø)
kernel/permission/acl/bucket/ak_2_account.go	100.00% <100.00%> (ø)
kernel/permission/acl/bucket/contract.go	100.00% <100.00%> (ø)
bcs/consensus/xpoa/xpoa.go	51.26% <0.00%> (-1.02%)	:arrow_down:
bcs/ledger/xledger/tx/mempool.go	42.06% <0.00%> (-0.28%)	:arrow_down:
kernel/permission/acl/manager.go	0.00% <0.00%> (ø)
... and 1 more

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