Add static credentialstore datasource

[AdamBouhmad]

Inspired by @grantorchard's scope datasource PR, I put together a first pass for the static cred store. Still needing to write tests & add documentation.

The static cred store datasource currently will allow the discovery of the resource by it's name, and will additionally return back the description of the resource.

data "boundary_credential_store_static" "test" {
  name     = "demo"
  scope_id = "p_jerZbKEwuL"
}

output "boundary_credential_store_id" {
  value = data.boundary_credential_store_static.test.id)
}

output "boundary_credential_store_name" {
  value = data.boundary_credential_store_static.test.name)
}

output "boundary_credential_store_description" {
  value = data.boundary_credential_store_static.test.description
}

----

Apply complete! Resources: 0 added, 0 changed, 0 destroyed.

Outputs:

boundary_credential_store_description = "testing!"
boundary_credential_store_id = "csst_qWsGl3OoHW"
boundary_credential_store_name = "demo"

[moduli]

I believe we're technically listing here instead of reading. I do see that's the message we have for scopes. We may want to modify that one.

Suggested change

	return diag.Errorf("error calling read static credential store: %v", err)
	return diag.Errorf("error calling list static credential store: %v", err)

[moduli]

nit: newline

Suggested change

	}
	func setFromStaticCredentialStoreReadResponseMap(d *schema.ResourceData, raw map[string]interface{}, fromRead bool) error {
	}
	func setFromStaticCredentialStoreReadResponseMap(d *schema.ResourceData, raw map[string]interface{}, fromRead bool) error {

[moduli]

nit: newline

Suggested change

	}
	func dataSourceCredentialStoreStaticRead(ctx context.Context, d *schema.ResourceData, meta interface{}) diag.Diagnostics {
	}
	func dataSourceCredentialStoreStaticRead(ctx context.Context, d *schema.ResourceData, meta interface{}) diag.Diagnostics {

[moduli]

I'm not sure I follow how to break down these resources. What's the reason for creating a specific boundary_credential_store_static data source as opposed to a boundary_credential_store one?