dont copy app routes to public dir, vary header

[leoortizz]

Description

• Add RSC headers to /app routes(extracted into Add Next.js RSC Vary header to app router routes #6662)
• Do not ship static /app routes to fix prefetching, so it goes to CF instead of CDN. Fixes prefetch.

Scenarios Tested

Sample Commands

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 62.50000% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 54.80%. Comparing base (0b770fe) to head (6e14565).
Report is 2 commits behind head on master.

Files	Patch %	Lines
src/frameworks/next/utils.ts	20.00%	0 Missing and 4 partials ⚠️
src/frameworks/next/index.ts	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6617   +/-   ##
=======================================
  Coverage   54.79%   54.80%           
=======================================
  Files         359      359           
  Lines       25059    25074   +15     
  Branches     5166     5170    +4     
=======================================
+ Hits        13732    13742   +10     
- Misses      10090    10092    +2     
- Partials     1237     1240    +3     

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