Refactored code to move default logic from the State class to the StatefulWidget

[awhitford]

• Moved _duration and _pause defaults to the StatefulWidget.
• Added assertions to ensure proper usage.
• Removed unused textWidgetList variables.
• Reordered imports.
• Tweaked indention.
• Declared _texts final.
• Added const keywords.

[codecov]

Codecov Report

Merging #131 into master will decrease coverage by 4.64%.
The diff coverage is 47.93%.

@@            Coverage Diff             @@
##           master     #131      +/-   ##
==========================================
- Coverage   68.86%   64.22%   -4.65%     
==========================================
  Files           8        8              
  Lines         713      763      +50     
==========================================
- Hits          491      490       -1     
- Misses        222      273      +51     

Impacted Files	Coverage Δ
lib/src/typewriter.dart	50.00% <21.42%> (-4.91%)	⬇️
lib/src/typer.dart	56.47% <27.27%> (-6.83%)	⬇️
lib/src/wavy.dart	64.46% <40.00%> (-3.06%)	⬇️
lib/src/fade.dart	56.66% <50.00%> (-6.63%)	⬇️
lib/src/scale.dart	59.59% <57.14%> (-7.08%)	⬇️
lib/src/rotate.dart	61.60% <57.89%> (-4.73%)	⬇️

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[SirusCodes]

Idk why do we need this anyways pause is constant..?

[awhitford]

YES! You're right! The refactoring helps make this crystal clear.

I'll go one step further... Why should _texts exist? It should simply reference widget.text.

I did not remove it because I wondered if there was a grand agenda to its existence. (🤔 I often wonder, "What was the original author thinking?")

I'm happy to reconsider removing it, but I would prefer doing it as a follow-up PR because it will impact other classes and the recent emoji-related changes may need to be tweaked. (I like to avoid too many ideas in a PR because it makes it more challenging to understand what was changed and why.)

[SirusCodes]

Yaa I also felt that but I haven't included it WavyAnimatedTexKit, maybe it was a thing that all the authors that it might have some use can but never had one 🤔 @aagarwal1012 do you have any idea?

[SirusCodes]

I have seen the code but not ran it(trusting @awhitford with it)