This commit introduces significant updates to enhance the handling of proxies within the server configuration and adds support for load balancing strategies.

Changes:
- Updated API tests to reflect changes from a single `Proxy` to a list of `Proxies`.
- Adjusted initialization and configuration of proxies in `run.go` to support multiple proxies and load balancer strategies.
- Updated configuration files to include new fields for multiple proxies and load balancer strategies.
- Enhanced global configuration validation for clients, pools, and proxies.
- Added new `loadBalancer` section in `gatewayd.yaml` for rules and strategies.
- Implemented load balancing strategy selection and Round Robin strategy.
- Added tests for load balancer strategies.
- Added new error type `ErrorCodeLoadBalancerStrategyNotFound`.
- Improved proxy connection handling and added informative comments.

Configuration Example:
- Updated `gatewayd.yaml` to reflect new support for multiple proxies and load balancer strategies.
- Ensure to update your configuration files accordingly.

Testing:
- Updated existing tests and added new tests for multi-proxy and load balancing functionality.
- Verified configuration validation for proxies and load balancers.

Impact:
- Improved flexibility and scalability of server configuration.
- Enabled robust proxy management and efficient load distribution.

Update errors/errors.go

Co-authored-by: Mostafa Moradian <[email protected]>
Signed-off-by: sina <[email protected]>

fixed review problems

- Change pools, clients, and proxies to use map[string]map[string] instead of map[string]
- Update related code for compatibility with new nested map structure

remvoed server 2 from gatewatd.yaml file

…iles

Updated variable names in the API, test files, run command, and configuration files to improve code readability and maintainability. Key changes include:

1. **api.go**:
   - Renamed `configurationGroupPools` to `configGroupPools` for clarity.

2. **api_helpers_test.go, api_test.go**:
   - Updated to use `config.DefaultConfigurationBlock` instead of `config.DefaultPool` and `config.DefaultProxy` for better naming consistency.

3. **run.go**:
   - Changed iteration variables to `configGroup` and `configBlockName` for better descriptive naming.
   - Updated logging and error handling to use `configBlockName`.
   - Modified span attribute naming for tracing proxy creation.

4. **config.go**:
   - Updated `DefaultPool`, `DefaultClient`, and `DefaultProxy` to `DefaultConfigurationBlock` in the `LoadDefaults` function.
   - Enhanced configuration parsing logic to handle `DefaultConfigurationBlock` appropriately and ensure robust error handling.

5. **constants.go**:
   - Renamed `DefaultClient`, `DefaultPool`, and `DefaultProxy` to `DefaultConfigurationBlock`.
   - Retained other configuration constants for environment prefix, tracer name, and configuration filenames.

These changes enhance the codebase by standardizing variable names, improving readability, and making the code easier to maintain.

- Enhanced the Client struct by adding YAML tags to all fields, ensuring compatibility with YAML parsers.
- Added YAML tags to the Size field in the Pool struct.
- Included YAML tags for the HealthCheckPeriod field in the Proxy struct.

These changes address limitations of the YAML parser and ensure proper serialization and deserialization of configuration data.

Co-authored-by: Mostafa Moradian <[email protected]>
Signed-off-by: sina <[email protected]>

- Modified the GetServers endpoint to return the current load balancer configuration for each server.
- Added a new field "loadBalancer" to the server details, including the load balancer strategy name.
- Updated unit tests to validate the new "loadBalancer" field in the API response.
- Adjusted test setup to include the default load balancer strategy configuration.

Renamed short variable names used in type assertions to longer, more descriptive names to resolve golint warnings about variable name length.

…strategies.