feat: add server configuration

[markphelps]

Fixes: FLI-1338

• Make server configurable with addr, port, protocol, etc
• Make setDefaults and validate run automatically for types that implement them in the config struct
• Standardize some error messages
• Added some configuration documentation for the docs site

workspace/glu - [api-config●] » GLU_SERVER_PORT=8081 go run ./examples/fakedata/...
2024/11/18 14:29:48 WARN could not locate glu.yaml
time=2024-11-18T14:29:48.326-05:00 level=INFO msg="starting server" addr=0.0.0.0:8081

[GeorgeMac]

Nice. Have some feedback. This is currently breaking defaults / validation for Credentials and Sources (we must be nearing test time 😂).

For example, when running this code with our internal pipeline. I see the following error when I use basic auth without a password:

➜  go run ./cmd/glu/. inspect
panic: building pipeline: git "foundation": performing initial fetch: invalid auth method

With either of the suggestions below this becomes:

➜  go run ./cmd/glu/. inspect
panic: configuring pipeline: both username and password need to be provided for basic auth

[markphelps]

@GeorgeMac I think I addressed all feedback and even added some basic unit tests for the processValue func

[GeorgeMac]

Sick