feat(source/alloydb, source/cloud-sql-postgres,source/cloud-sql-mysql,source/cloud-sql-mssql): Use project from env for alloydb and cloud sql control plane tools (#1588)

## Description

---
This change introduces the `DefaultProject` field for the
`alloydb-admin` and `cloud-sql-admin` sources. This field allows the
alloydb and cloud sql control plane tools to use the project value from
the environment variables (Ex: `ALLOYDB_POSTGRES_PROJECT`) if it is
already set instead of asking the user.

## PR Checklist

---
> Thank you for opening a Pull Request! Before submitting your PR, there
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- [x] Make sure you reviewed

[CONTRIBUTING.md](https://github.com/googleapis/genai-toolbox/blob/main/CONTRIBUTING.md)
- [x] Make sure to open an issue as a

[bug/issue](https://github.com/googleapis/genai-toolbox/issues/new/choose)
before writing your code! That way we can discuss the change, evaluate
  designs, and agree on the general idea
- [x] Ensure the tests and linter pass
- [x] Code coverage does not decrease (if any source code was changed)
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🛠️ Fixes: https://github.com/gemini-cli-extensions/alloydb/issues/47

---------

Co-authored-by: Averi Kitsch <akitsch@google.com>

internal/tools/cloudsql/cloudsqlwaitforoperation/cloudsqlwaitforoperation.go

@@ -122,8 +122,16 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		return nil, fmt.Errorf("invalid source for %q tool: source kind must be `cloud-sql-admin`", kind)
 	}
 
+	project := s.DefaultProject
+	var projectParam tools.Parameter
+	if project != "" {
+		projectParam = tools.NewStringParameterWithDefault("project", project, "The GCP project ID. This is pre-configured; do not ask for it unless the user explicitly provides a different one.")
+	} else {
+		projectParam = tools.NewStringParameter("project", "The project ID")
+	}
+
 	allParameters := tools.Parameters{
-		tools.NewStringParameter("project", "The project ID"),
+		projectParam,
 		tools.NewStringParameter("operation", "The operation ID"),
 	}
 	paramManifest := allParameters.Manifest()