Clean `config` parameters

[wthrajat]

Aims to fix https://github.com/citadel-tech/coinswap/issues/248

• [x] Removed internal parameters from MakerConfig and TakerConfig that should not be exposed to users.
• [x] Hardcoded default values for internal parameters in maker/server.rs.
• [x] Hardcoded default values for internal parameters in taker/api.rs.
• [x] Replaced separate directory_server_onion_address and directory_server_clearnet_address fields with a unified directory_server_address field for both MakerConfig and TakerConfig.
• [x] Set required_confirms to a default value of 1 for MakerConfig, removing it from user-facing configuration options.
• [X] Adjusted the code to use the constants rather than the struct fields.
• [x] Added documentation wherever needed.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 58.49057% with 22 lines in your changes missing coverage. Please review.

Project coverage is 74.80%. Comparing base (2f9f0aa) to head (0bbacec). Report is 9 commits behind head on master.

Files with missing lines	Patch %	Lines
src/taker/api.rs	48.00%	13 Missing :warning:
src/maker/server.rs	44.44%	5 Missing :warning:
src/taker/routines.rs	20.00%	4 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #276 +/- ## ========================================== - Coverage 79.65% 74.80% -4.86% ========================================== Files 32 32 Lines 4945 4362 -583 ========================================== - Hits 3939 3263 -676 - Misses 1006 1099 +93 ```

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