DOC: Create issue/pr templates

.github/ISSUE_TEMPLATE/bug_report.md

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+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+### ⛔ What happened?
+
+-
+
+### 🎯 Reproduction Steps
+
+<!-- Please write what you did to cause the issue if you are able to reproduce it. -->
+-
+
+### 💡 Expected Behavior / Solution
+
+<!-- Please write about the appropriate behavior and, if possible, your solution. -->
+-

.github/ISSUE_TEMPLATE/feature-refactoring-request.md

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+---
+name: Feature/Refactoring request
+about: Suggest an idea for this project
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+### 🔍 Description
+
+<!--  Please describe the feature you want to see and why it needs. -->
+-
+
+### ⏰ Implementation Idea
+
+<!-- Please write about how you'd like to implement. -->
+-

.github/PULL_REQUEST_TEMPLATE.md

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+### 🔗 Related Issue
+
+<!-- Please link related issue. ex) https://github.com/naver/arcus-java-client/issues/{issue_number} -->
+-
+
+### ⌨️ What I did
+
+<!-- Please describe this PR and what you've been working on. -->
+-