Add macros for global beginning and end of all times dates

[tkiehn]

Description

The global variables for beginning and end of all times as a date are currently set as dictionaries inside the dbt_project.yml.
This PR introduces the macros that parse these variables and call them in the ghost_records_per_datatype.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• This change requires a documentation update
  - Global variables need to be updated in the Wiki

How Has This Been Tested?

Pipeline when opening this PR

Checklist:

• I have performed a self-review of my code
• I have made corresponding changes to the documentation or included information that needs updates (e.g. in the Wiki)

[remoteworkflow]

Link to workflow summary: https://github.com/ScalefreeCOM/datavault4dbt-ci-cd/actions/runs/10697407533

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RESULTS for Synapse:
✅ dbt-tests
✅ dbt-macro-tests

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RESULTS for Postgres:
✅ dbt-tests
✅ dbt-macro-tests

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RESULTS for BigQuery:
✅ dbt-tests
✅ dbt-macro-tests

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RESULTS for Redshift:
✅ dbt-tests
✅ dbt-macro-tests

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RESULTS for Snowflake:
✅ dbt-tests
✅ dbt-macro-tests

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RESULTS for Exasol:
❌ dbt-tests
❌ dbt-macro-tests

[remoteworkflow]

Link to workflow summary: https://github.com/ScalefreeCOM/datavault4dbt-ci-cd/actions/runs/10697411534

---

RESULTS for Synapse:
✅ dbt-tests
✅ dbt-macro-tests

---

RESULTS for Postgres:
✅ dbt-tests
✅ dbt-macro-tests

---

RESULTS for BigQuery:
✅ dbt-tests
✅ dbt-macro-tests

---

RESULTS for Redshift:
✅ dbt-tests
✅ dbt-macro-tests

---

RESULTS for Snowflake:
✅ dbt-tests
✅ dbt-macro-tests

---

RESULTS for Exasol:
❌ dbt-tests
✅ dbt-macro-tests