feat(transport): add endpoint option for server

[youzhixiaomutou]

Description (what this PR does / why we need it):

transport/server.go exposes an Endpoint() option that allows to specify the endpoint when defining the server, instead of manually specifying it for each server when creating a new app.

kratos/transport/grpc/server.go

Line 119 in 32b1d13

endpoint *url.URL

Which issue(s) this PR fixes (resolves / be part of):

fixes/resolves #2902

Other special notes for the reviewers:

[codecov-commenter]

Codecov Report

Merging #2904 (163f646) into main (db2a565) will decrease coverage by 0.13%.
The diff coverage is 0.00%.

❗ Current head 163f646 differs from pull request most recent head ba36d3f. Consider uploading reports for the commit ba36d3f to get more accurate results

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@@            Coverage Diff             @@
##             main    #2904      +/-   ##
==========================================
- Coverage   84.50%   84.38%   -0.13%     
==========================================
  Files          88       88              
  Lines        3970     3976       +6     
==========================================
  Hits         3355     3355              
- Misses        438      445       +7     
+ Partials      177      176       -1     

Impacted Files	Coverage Δ
transport/grpc/server.go	81.37% <0.00%> (-2.47%)	⬇️
transport/http/server.go	73.07% <0.00%> (-1.44%)	⬇️

... and 2 files with indirect coverage changes

[shenqidebaozi]

LGTM