Add tests for links/base and links/bigquery in Google provider - #68066

issue: #35442

Added test_base.py

Tests for BaseGoogleLink — the shared base class all Google links inherit from. Covers:

• xcom_key property returns self.key
• persist() pushes the correct key/value to XCom
• get_config() returns None when no config found; merges extra_links_params from operator with XCom value; XCom takes precedence over operator params
• _format_link() prepends BASE_LINK for relative paths; returns "" on missing format key; returns absolute URLs unchanged
• get_link() returns "" when no config; passes through existing http URLs without re-formatting; formats URL from config

Added test_bigquery.py

Tests for BigQueryDatasetLink, BigQueryTableLink, BigQueryJobDetailLink. Each class covers:

• Class attributes (key, name, format_str)
• persist() calls xcom_push with correct key and values
• _format_link() produces the expected URL

Was generative AI tooling used to co-author this PR?

• Yes (claude sonnet 4.6)

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