Add SAM Validate stage when sceptre validate is run

[rohits2290]

Subject of the issue

Describe your issue here.

Your environment

• version of sceptre (sceptre --version)
  Sceptre, version 4.5.2

• version of python (python --version)
  Python 3.11.8

• which OS/distro
  MacOS
  CodeBuild - aws/codebuild/amazonlinux2-x86_64-standard:5.0

Steps to reproduce

Currently when you run sceptre validate
Sceptre attempts to build, package and upload to S3.
SAM has an option to simply validate the template - https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-cli-command-reference-sam-validate.html

This could be a step after sceptre renders j2 templates or simple yaml/json serverless templates.

Expected behaviour

Should only validate the template.

Actual behaviour

Instead, sceptre builds, packages and uploads packages to S3.