feature: add projectPkg and servicePkg parameters to gen api template(go module)

[6xiaowu9]

Issue: #3785

In actual application scenarios, we should allow users to use the two parameters projectPkg and rootPkg when customizing templates.

add parameters to template:

• projectPkg
• servicePkg

handler example:

package {{.PkgName}}

import (
        "net/http"

        "github.com/zeromicro/go-zero/rest/httpx"
        "{{.ServicePkg}}/internal/response"
        {{.ImportPackages}}
)

func {{.HandlerName}}(svcCtx *svc.ServiceContext) http.HandlerFunc {
        return func(w http.ResponseWriter, r *http.Request) {
                {{if .HasRequest}}var req types.{{.RequestType}}
                if err := httpx.Parse(r, &req); err != nil {
                        httpx.ErrorCtx(r.Context(), w, err)
                        return
                }

                {{end}}l := {{.LogicName}}.New{{.LogicType}}(r.Context(), svcCtx)
                {{if .HasResp}}resp, {{end}}err := l.{{.Call}}({{if .HasRequest}}&req{{end}})
                {{if .HasResp}}response.Response(w, resp, err){{else}}response.Response(w, nil, err){{end}}
        }
}

other example:

package {{.pkgName}}

import (
        "{{.projectPkg}}/xxx"
        "{{.servicePkg}}/xxx"
)

just handler is {{.ServicePkg}} and {{.ProjectPkg}}

[6xiaowu9]

@kevwan Hi, I hope you can help me see if this change is reasonable and correct.

[kesonan]

Go module variable has already open for go template on api/rpc generating. pls see #3798

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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Additional details and impacted files

see 7 files with indirect coverage changes