sap_hana_install: Enhance with delegated tasks to achieve proper idempotency for addhosts

[marcelmamula]

NOTE

New re-imagined approach using Inventory to solve delegation issues with package installations is available at #1126.

Premise

Current workflow of sap_hana_install does not execute any tasks on addhosts, be it for new or existing systems, resulting in inconsistent system. All tasks are executed only on managed node, including important configuration tasks like firewall, selinux, etc.

Changes

This PR introduces split of role workflow into separate runner files for Install and Addhosts along with range of changes:

• Add new tasks files that need to be delegated to addhosts, because Ansible does not allow loop and delegate_to in same task.
  • NOTE: delegate_to also cannot be on same level as include_tasks so it is set inside of actual task file. It can be inside of block.
• Add missing tasks:
  • Create user sapadm on addhosts, because it is required when hdblcm is running in addhosts mode as it cannot use root SSH.
• Add missing validations for addhosts string for quality and contents
• Renamed most of the tasks to keep same naming structure to divide Pre-Tasks, Post-Tasks, Install and Addhosts.
• Remove unused task files

Tests

This was tested on SLES 15 SP6 on AWS with AP4S sap_hana_scaleout scenario tuning inputs to test:
NOTE: Variables in table below were shortened to fit GitHub window size.

new_system	fact_is_installed	addhosts	Result
true	false	undefined	SUCCESS
true	false	defined	SUCCESS
true	true	undefined	SUCCESS (Post-Tasks)
true	true	defined	SUCCESS (Post-Tasks with information that addhosts were skipped)
false	false	undefined	FAIL (missing sap_hana_install_addhosts
false	false	defined	FAIL (must be installed)
false	true	undefined	FAIL (missing sap_hana_install_addhosts
false	true	defined	SUCCESS

Implemented workflow diagram

graph TD;
    A[Validation and checks] --> B{sap_hana_install_new_system};
    B  -- true --> C{__sap_hana_install_fact_is_installed};
    C -- true --> D[Execute only Post-Tasks];
    C -- false --> E[Execute all tasks];
    D --> F{sap_hana_install_addhosts};
    F -- Defined --> G[Inform about sap_hana_install_new_system false];

    B  -- false --> I{__sap_hana_install_fact_is_installed};
    I -- true --> J{__sap_hana_install_fact_addhosts_hosts_new length > 0};
    I -- false --> K[Fail];
    J -- true --> L[Execute all tasks];
    J -- false --> M[Execute only Post-Tasks];

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