perf(MuxPath): prefix and fullpath support rewrite_target

[aniaan]

close: #552

[codecov-commenter]

Codecov Report

Merging #553 (03aef3a) into main (0cd6b15) will increase coverage by 0.00%.
The diff coverage is 88.63%.

@@           Coverage Diff           @@
##             main     #553   +/-   ##
=======================================
  Coverage   78.51%   78.51%           
=======================================
  Files          94       95    +1     
  Lines       10878    10940   +62     
=======================================
+ Hits         8541     8590   +49     
- Misses       1850     1867   +17     
+ Partials      487      483    -4     

Impacted Files	Coverage Δ
pkg/object/httpserver/mux.go	66.12% <76.19%> (+2.87%)	⬆️
pkg/object/httpserver/spec.go	13.33% <100.00%> (+6.19%)	⬆️
pkg/util/stringtool/stringtool.go	42.85% <100.00%> (ø)
pkg/cluster/cluster.go	53.06% <0.00%> (+0.94%)	⬆️

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[localvar]

This is incorrect, for example:
if both mp.path and mp.pathPrefix are not empty and the request matches mp.pathPrefix, the path should be rewritten at L277, but was actually rewritten at L272, which is wrong.

[aniaan]

I missed the point that path and prefix and regexp can co-exist, I previously thought they were a mutually exclusive relationship, I'll fix that

[samutamm]

This change could be documented here: controllers.md . Old doc

Use pathRegexp.[ReplaceAllString](https://golang.org/pkg/regexp/#Regexp.ReplaceAllString)(path, rewriteTarget) to rewrite request path

New doc:

Use pathRegexp.[ReplaceAllString](https://golang.org/pkg/regexp/#Regexp.ReplaceAllString)(path, rewriteTarget) or pathPrefix [strings.Replace](https://pkg.go.dev/strings#Replace) to rewrite request path

[aniaan]

1. If path, prefix, and regexp are empty, but rewriteTarget is not empty, the newly created spec will fail to verify. For the existing spec, rewriteTarget will not take effect, because I didn't expect the three to be empty at present, but The scenario where the path is still to be rewritten, so a check is added
2. There is also the handleRewrite function, you can see if it is appropriate to do so

rule:

1. if "match path" and rewriteTarget not empty, request.setPath(rewriteTarget)
2. if "match prefix" and rewriteTarget not empty, request.setPath(strings.Replace(path, prefix, 1))
3. if "match regexp" and rewriteTarget not empty, request.setPath(regexp.Replace(path, regexpRepl))

@samutamm @localvar