sql: use SQL-standard names for built-in regtype values

[Alignyx]

Fixes #97456.

Casting an array type OID to regtype currently exposes the internal catalog name instead of the SQL type name. For example:

SELECT 1016::oid::regtype;

This returns _int8; PostgreSQL returns bigint[]. The OID itself is correct: casting the result back to oid still gives 1016. The discrepancy is in the name attached to the regtype value.

performIntToOidCast resolves built-in type OIDs through types.OidToType, then uses PGName() when constructing the result. That method supplies catalog names, including the underscore-prefixed array names. The built-in branch already documents that it should return SQL-standard names, but the formatter did not implement that behavior.

This change uses SQLStandardName() at that point. The existing formatter derives an ordinary array name from its element type's SQL name and appends [], so _int8 becomes bigint[], _int4 becomes integer[], and _float8 becomes double precision[]. Reusing the type formatter also handles scalar aliases consistently: int4 displays as integer and int8 as bigint. This is preferable to stripping an underscore, which would still leave catalog spellings such as int8 in the result. The formatter already has separate cases for int2vector, oidvector, and anyarray.

There is one accompanying correction in the shared formatter. any and anyelement both belong to AnyFamily, which previously always formatted as anyelement. Checking for oid.T_any keeps their names distinct when the cast starts using this formatter.

The cast still constructs the result with the original OID and regtype semantic type. Built-in types continue to use the existing lookup, and user-defined types continue through resolveOID, including its search-path-aware qualification. No catalog entries or type identities change.

Regression coverage includes the reported array OID, integer-to-regtype casts, an OID round trip, several other array element types, scalar aliases, pseudo-types, vector types, NULL, and the zero OID. The SQL expression cases run through both the optimized and non-optimized paths of TestEval. A separate type-package test checks the exact names of any, anyelement, and anyarray.

Validation:

• The complete //pkg/sql/sem/eval:eval_test and //pkg/sql/types:types_test targets pass locally.
• The new regression tests fail on the unchanged parent revision 8812064a015d2faf99d3fc7e15880f94042954b0: the cast cases expose catalog names, and the type formatter returns anyelement for any.
• Go formatting was checked with crlfmt; git diff --check passes. The package tests used --norun_validations; the repository-wide test suite and full lint/generation checks were not run.

Release note (bug fix): Fixed the names displayed when casting built-in type OIDs to regtype. Array types now use SQL names such as bigint[] instead of internal catalog names such as _int8. Scalar types use their corresponding SQL names, such as integer for int4.

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