[rust-compiler] Allow Flow TypeCastExpression in PatternLike

[poteto]

PatternLike already had the four TS cast wrapper variants
(TSAsExpression, TSSatisfiesExpression, TSNonNullExpression,
TSTypeAssertion) so that (x as T) = ... style assignment
targets and parameter positions are representable. Flow's analogue
of those wrappers is TypeCastExpression, e.g.

function f(fallback: React.Node = <></>): void { ... }

where fallback: React.Node = <></> reaches the converter as an
AssignmentPattern whose left is a TypeCastExpression over the
binding identifier. The round-trip test rejected this with:

Deserialization error: unknown variant `TypeCastExpression`,
expected one of `Identifier`, `ObjectPattern`, ... `TSTypeAssertion`

Add TypeCastExpression as the sixth expression-like variant of
PatternLike, reusing the existing
crate::expressions::TypeCastExpression struct (which already
matches Babel's { expression, typeAnnotation } shape and is
already handled on the expression side).

Wire the new variant through every exhaustive PatternLike match
the workspace requires, mirroring the existing TS wrapper
handling at each site:

• react_compiler_ast/src/visitor.rs::walk_pattern: recurse into
  the inner expression.
• react_compiler_lowering/src/find_context_identifiers.rs: record
  the TS-faithful [FindContextIdentifiers] Cannot handle Object destructuring assignment target TypeCastExpression Todo.
• react_compiler_lowering/src/build_hir.rs: fall-through arms in
  pattern_like_loc, pattern_declares_name,
  collect_binding_names_from_pattern, lower_assignment, and the
  inner-function-parameter walker.
• react_compiler/src/entrypoint/program.rs: fall-through arms in
  calls_hooks_or_creates_jsx_in_pattern and
  is_valid_props_annotation.
• react_compiler/src/entrypoint/validate_source_locations.rs:
  fall-through arms in the original/generated pattern collectors.
• react_compiler_swc/src/convert_ast_reverse.rs: convert to
  Pat::Expr (mirrors TS wrappers); use __unknown__ placeholder
  in the assign-target path.
• react_compiler_oxc/src/convert_ast.rs and
  react_compiler_oxc/src/convert_ast_reverse.rs: equivalent
  no-op / placeholder arms in the OXC frontend.

No new behavior is introduced. The reverse converters fall through
the same way they do for TS wrappers, and the Todo emission
matches the TS reference behavior for an unsupported assignment-
target wrapper.

Fixes 1 round-trip parity failure:

• error.todo-round2_fn_type_component_to_other.js

Test plan:

• bash compiler/scripts/test-babel-ast.sh:
  Before: 1778/1780 round-trip (2 failures)
  After: 1779/1780 round-trip (1 failure, 1 fixed)
  Remaining failure (lone-surrogate-string-values.js) is unrelated;
  handled in the next commit as a skip-list entry pending WTF-8
  string-representation work.
• cargo build: clean across the workspace.