[MM-28422] Enable processing of import files through API (#16062)

* Implement unzip function

* Implement FileSize method

* Implement path rewriting for bulk import

* Small improvements

* Add ImportSettings to config

* Implement ListImports API endpoint

* Enable uploading import files

* Implement import process job

* Add missing license headers

* Address reviews

* Make path sanitization a bit smarter

* Clean path before calculating Dir

* [MM-30008] Add mmctl support for file imports (#16301)

* Add mmctl support for import files

* Improve test

* Remove unnecessary handlers

* Use th.TestForSystemAdminAndLocal

* Make nouser id a constant

model/client4.go

@@ -543,6 +543,10 @@ func (c *Client4) GetGroupSyncablesRoute(groupID string, syncableType GroupSynca
 	return fmt.Sprintf("%s/%ss", c.GetGroupRoute(groupID), strings.ToLower(syncableType.String()))
 }
 
+func (c *Client4) GetImportsRoute() string {
+	return "/imports"
+}
+
 func (c *Client4) DoApiGet(url string, etag string) (*http.Response, *AppError) {
 	return c.DoApiRequest(http.MethodGet, c.ApiUrl+url, "", etag)
 }
@@ -5754,6 +5758,15 @@ func (c *Client4) UpdateCloudCustomerAddress(address *Address) (*CloudCustomer,
 	return customer, BuildResponse(r)
 }
 
+func (c *Client4) ListImports() ([]string, *Response) {
+	r, err := c.DoApiGet(c.GetImportsRoute(), "")
+	if err != nil {
+		return nil, BuildErrorResponse(r, err)
+	}
+	defer closeBody(r)
+	return ArrayFromJson(r.Body), BuildResponse(r)
+}
+
 func (c *Client4) GetUserThreads(userId string, options GetUserThreadsOpts) (*Threads, *Response) {
 	v := url.Values{}
 	if options.Since != 0 {