Create introduction page

[ricky9667]

Description

This PR creates an introduction page for users to setup keyboard easier.

How to verify

1. Setup page should show each section after the last button is tapped.
2. Textfield in the introduction page should verify if user types `R U R' U', and shows dialog if true.

Screenshots / Videos

create-introduction-page-demo.mov

[codecov]

Codecov Report

Attention: Patch coverage is 44.72050% with 89 lines in your changes missing coverage. Please review.

Project coverage is 45.45%. Comparing base (2472714) to head (1f3beec).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...hu/hushkeyboard/introduction/IntroductionScreen.kt	0.00%	36 Missing ⚠️
.../rickyhu/hushkeyboard/introduction/Step3Section.kt	43.18%	20 Missing and 5 partials ⚠️
.../rickyhu/hushkeyboard/introduction/Step1Section.kt	71.87%	5 Missing and 4 partials ⚠️
.../rickyhu/hushkeyboard/introduction/Step2Section.kt	71.87%	5 Missing and 4 partials ⚠️
.../java/com/rickyhu/hushkeyboard/main/MainNavHost.kt	0.00%	6 Missing ⚠️
...n/java/com/rickyhu/hushkeyboard/home/HomeScreen.kt	63.63%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #44      +/-   ##
==========================================
- Coverage   45.74%   45.45%   -0.29%     
==========================================
  Files          34       38       +4     
  Lines         693      836     +143     
  Branches      172      215      +43     
==========================================
+ Hits          317      380      +63     
- Misses        298      367      +69     
- Partials       78       89      +11     

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