Refactor agent modules

[thomaszhouan]

• The refactoring of agent package is finished. New agent classes can extends Agent base class for better code reuse and clarity.
• The old agent classes are compatible with those extended from the Agent base class
• Test classes are also refactored, and writing test is now simpler
• The bug in #116 is fixed
• Add logic for injected feature, including admin user, claiming coupon and issuing sharing code.

[codecov[bot]]

Codecov Report

Merging #119 into develop will increase coverage by 7.4%. The diff coverage is 73.5%.

@@            Coverage Diff             @@
##             develop   #119     +/-   ##
==========================================
+ Coverage       61.5%    69%   +7.4%     
- Complexity       343    391     +48     
==========================================
  Files             42     44      +2     
  Lines           1842   1992    +150     
  Branches         232    211     -21     
==========================================
+ Hits            1134   1375    +241     
+ Misses           626    545     -81     
+ Partials          82     72     -10

Impacted Files	Coverage Δ	Complexity Δ
...ain/java/controller/DietingChatbotApplication.java	0% <0%> (ø)	0 <0> (ø)	:arrow_down:
...hatbot/src/main/java/database/querier/Querier.java	64.9% <0%> (-0.5%)	34 <0> (ø)
...ting-chatbot/src/main/java/agent/PortionAsker.java	0% <0%> (-31.1%)	0 <0> (-4)
...chatbot/src/main/java/controller/ImageControl.java	2.1% <0%> (-20.1%)	2 <0> (-1)
...ot/src/main/java/controller/ChatbotController.java	65.1% <0%> (-0.5%)	18 <0> (ø)
...atbot/src/main/java/agent/IntentionClassifier.java	0% <0%> (ø)	0 <0> (ø)	:arrow_down:
...eting-chatbot/src/main/java/agent/MenuManager.java	100% <100%> (ø)	5 <5> (?)
.../src/main/java/database/keeper/CampaignKeeper.java	91.6% <100%> (+8.3%)	13 <1> (+1)	:arrow_up:
...g-chatbot/src/main/java/utility/TextProcessor.java	94.4% <100%> (+1.5%)	10 <4> (+4)	:arrow_up:
...ieting-chatbot/src/main/java/controller/State.java	93.3% <100%> (ø)	10 <0> (ø)	:arrow_down:
... and 16 more

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