use middleware to capture HTTP server metrics

[libotony]

Description

Using middleware to capture HTTP server metrics, added names for all paths, added feature that only records named path's metrics to avoid random API access potentially blowing up metrics db.

In this PR, dependency upgraded github.com/gorilla/mux v1.6.0 -> v1.8.1

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] New and existing E2E tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] I have not added any vulnerable dependencies to my code

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 75.00000% with 19 lines in your changes are missing coverage. Please review.

Project coverage is 62.58%. Comparing base (b18c7a6) to head (2cf99b2). Report is 1 commits behind head on master.

Files	Patch %	Lines
cmd/thor/main.go	0.00%	14 Missing :warning:
api/api.go	0.00%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #753 +/- ## ========================================== + Coverage 62.55% 62.58% +0.03% ========================================== Files 198 199 +1 Lines 18071 18093 +22 ========================================== + Hits 11304 11324 +20 - Misses 5683 5687 +4 + Partials 1084 1082 -2 ```

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[libotony]

@otherview @leszek-vechain Unit test added, covering both 200 and none-200 cases and also no named urls(metrics)