Fix: allow different service and container port

[Kolossi]

Description of your changes

copilot:all

This PR allows specifying a different port and containerPort to be used by the service created by a webservice component.

It also allows the gateway trait to use an existing service (in the usecase, the one created by the webservice) rather than creating one.

I have:

• Read and followed KubeVela's contribution process.
• Related Docs updated properly. In a new feature or configuration option, an update to the documentation is necessary.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

I've used this locally, and have taken care that this is a non-breaking change is new properties are not used.

Special notes for your reviewer

An example usecase is a dotnet workload in the webservice container where dotnet serves on port 5000, but the service is to be exposed for port 80 requests. Currently there is no way to achieve this with the standard component/traits.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.56%. Comparing base (1a001e5) to head (a1bb051).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6477      +/-   ##
==========================================
+ Coverage   65.54%   65.56%   +0.02%     
==========================================
  Files         183      183              
  Lines       23891    23891              
==========================================
+ Hits        15659    15665       +6     
+ Misses       6648     6645       -3     
+ Partials     1584     1581       -3     

Flag	Coverage Δ
core-unittests	55.36% <ø> (+0.04%)	⬆️
e2e-multicluster-test	31.12% <ø> (ø)

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