Support local Nominatim servers

[alexwhitedatamine]

Resolves issue #41 to support local Nominatim servers by adding a keyword argument nominatim_server to:

• bbox_to_poly
• geo_address_lookup
• geo_address_lookup_sf
• geo_lite
• geo_lite_sf
• reverse_geo_lite
• reverse_geo_lite_sf

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 80.00000% with 7 lines in your changes are missing coverage. Please review.

Project coverage is 97.78%. Comparing base (9122576) to head (9467736).

Files	Patch %	Lines
R/geo_address_lookup.R	75.00%	1 Missing :warning:
R/geo_address_lookup_sf.R	75.00%	1 Missing :warning:
R/geo_lite.R	80.00%	1 Missing :warning:
R/geo_lite_sf.R	83.33%	1 Missing :warning:
R/nominatim_check_access.R	75.00%	1 Missing :warning:
R/reverse_geo_lite.R	83.33%	1 Missing :warning:
R/reverse_geo_lite_sf.R	83.33%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #42 +/- ## ========================================== - Coverage 99.29% 97.78% -1.52% ========================================== Files 10 10 Lines 426 451 +25 ========================================== + Hits 423 441 +18 - Misses 3 10 +7 ```

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[dieghernan]

Thanks!