`vela def init-module` hardcoded `require github.com/oam-dev/kubevela
v1.9.0` in the generated go.mod. Scaffolded modules pinned the wrong
SDK whenever the installed vela tool drifted from v1.9.0, forcing users
to hand-edit go.mod after scaffolding.
Add version.ModuleRequireVersion() which returns the build-time
VelaVersion when it is a valid semver and falls back to a pinned
default for dev builds where VelaVersion is "UNKNOWN" (plain `go
build`) or "master" (Makefile default) — both invalid semver that
would otherwise break `go mod tidy` in the scaffolded module.
Signed-off-by: Jerrin Francis <jerrinfrancis7@gmail.com>
