Making static route more verbose if file not found

[tomaszdrozdz]

@ahopkins something like that ? (contnuation of #1941)

[codecov]

Codecov Report

Merging #1945 (684b6b6) into master (449bc41) will decrease coverage by 0.11%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #1945      +/-   ##
==========================================
- Coverage   92.81%   92.69%   -0.12%     
==========================================
  Files          29       29              
  Lines        3256     3259       +3     
  Branches      569      569              
==========================================
- Hits         3022     3021       -1     
- Misses        158      161       +3     
- Partials       76       77       +1     

Impacted Files	Coverage Δ
sanic/static.py	92.85% <66.66%> (-1.18%)	⬇️
sanic/server.py	81.05% <0.00%> (-0.57%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 449bc41...684b6b6. Read the comment docs.

[ahopkins]

Can we get these passing so we can include in the upcoming release?