feat: adjust video quality

[xiaoyuhen]

feat: adjust video quality

Description

we don't need to create a new MediaSource when the user switches video quality.

we remove the old buffer and append new video data When the user switches video quality.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[codecov-io]

Codecov Report

Merging #65 into master will decrease coverage by 0.42%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master      #65      +/-   ##
==========================================
- Coverage   52.08%   51.65%   -0.43%     
==========================================
  Files         123      123              
  Lines        1703     1717      +14     
==========================================
  Hits          887      887              
- Misses        816      830      +14

Impacted Files	Coverage Δ
packages/griffith-mp4/src/player.js	0% <0%> (ø)	⬆️
packages/griffith-mp4/src/mse/controller.js	0% <0%> (ø)	⬆️

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