[#12421] docs: Fix links after documentation restructure

[hutiefang76]

What changes were proposed in this pull request?

Repoint documentation links whose anchors were removed by #12327:

• catalog and schema operation links now target manage-catalogs-and-schemas.md;
• column type, default value, auto-increment, external type, and unparsed type links now target tables-and-views.md;
• the missing column type reference and related concepts are restored on the table concept page;
• two Trino connector links to the moved create-catalog section are corrected as well.

The restored type examples were checked against the current Java type factories and JSON
serialization tests.

Why are the changes needed?

PR #12327 moved or removed the linked sections but left references across catalog and connector
documentation pointing at the old anchors. Those links resolve to missing sections on the rendered
site.

Fix: #12421

Does this PR introduce any user-facing change?

Documentation links now open the intended sections, and the table concept page again documents
Gravitino column types and the external/unparsed compatibility types. There is no API or
configuration change.

How was this patch tested?

• Validated all 65 changed local Markdown links with anchors against their target files and
  headings.
• Verified that no removed manage-relational-metadata-using-gravitino.md anchor targeted by this
  issue remains.
• ./gradlew :api:test --tests org.apache.gravitino.rel.TestTypes :common:test --tests org.apache.gravitino.json.TestJsonUtils spotlessCheck
• ./gradlew :docs:build
• Built the current docs with the official apache/gravitino-site Docusaurus project using
  npm run build. The site still reports pre-existing warnings in historical/current docs, but
  none are for the links changed here.

[jerryshao]

Hi @hutiefang76, thanks a lot for your contributions. Can you please fix the conflicts?

[hutiefang76]

Resolved the conflict with the latest main. The only manual conflict was in docs/lakehouse-iceberg-catalog.md; I kept the current wording from main and updated its obsolete target to tables-and-views.md#external-type.

The branch now rebases cleanly, has no conflict markers or whitespace errors, and the changed relative-link targets exist.

[github-actions]

Code Coverage Report

Overall Project	68.67%	🟢
Files changed	No Java source files changed	-

Module	Coverage
aliyun	1.72%	🔴
api	49.31%	🟢
authorization-common	85.96%	🟢
aws	42.04%	🟢
azure	2.47%	🔴
catalog-common	9.92%	🔴
catalog-fileset	79.77%	🟢
catalog-glue	68.95%	🟢
catalog-hive	79.4%	🟢
catalog-jdbc-common	45.7%	🟢
catalog-jdbc-doris	81.8%	🟢
catalog-jdbc-mysql	79.33%	🟢
catalog-jdbc-postgresql	83.39%	🟢
catalog-jdbc-starrocks	79.16%	🟢
catalog-kafka	77.01%	🟢
catalog-lakehouse-generic	59.18%	🟢
catalog-lakehouse-hudi	79.1%	🟢
catalog-lakehouse-iceberg	85.86%	🟢
catalog-lakehouse-paimon	84.23%	🟢
catalog-model	77.72%	🟢
cli	44.48%	🟢
client-java	78.56%	🟢
common	52.75%	🟢
core	83.63%	🟢
filesystem-hadoop3	77.28%	🟢
flink	0.0%	🔴
flink-common	48.68%	🟢
flink-runtime	0.0%	🔴
gcp	14.12%	🔴
hadoop-auth	68.0%	🟢
hadoop-common	12.7%	🔴
hive-metastore-common	53.4%	🟢
iceberg-aliyun-bundle	0.0%	🔴
iceberg-common	64.75%	🟢
iceberg-rest-server	75.03%	🟢
idp-basic	86.02%	🟢
integration-test-common	0.0%	🔴
jobs	62.92%	🟢
lance-common	31.75%	🔴
lance-rest-server	63.47%	🟢
lineage	53.02%	🟢
optimizer	83.24%	🟢
optimizer-api	21.95%	🔴
server	87.25%	🟢
server-common	79.41%	🟢
spark	28.57%	🔴
spark-common	45.89%	🟢
tencent	69.84%	🟢
trino-connector	40.29%	🟢