gccrs: ast: Move pattern implementation out of rust-ast

gccrs: ast: Move pattern implementation out of rust-ast

Move rust-pattern implementation out of rust-ast.cc in their own file.

gcc/rust/ChangeLog:

	* Make-lang.in: Add two new files to the list of sources.
	* ast/rust-ast-full.h: Add new ast formatting header.
	* ast/rust-ast.cc (enum indent_mode): Move formatting function
	to it's own file.
	(indent_spaces): Likewise.
	(get_string_in_delims): Likewise.
	(enum AttrMode): Likewise.
	(get_mode_dump_desc): Likewise.
	(append_attributes): Likewise.
	(unquote_string): Likewise.
	(GroupedExpr::as_string): Move pattern implementation to it's
	own file.
	(RangePattern::as_string): Likewise.
	(RangePatternBoundLiteral::as_string): Likewise.
	(SlicePattern::as_string): Likewise.
	(AltPattern::as_string): Likewise.
	(TuplePatternItemsMultiple::as_string): Likewise.
	(TuplePatternItemsRanged::as_string): Likewise.
	(TuplePattern::as_string): Likewise.
	(StructPatternField::as_string): Likewise.
	(StructPatternFieldIdent::as_string): Likewise.
	(StructPatternFieldTuplePat::as_string): Likewise.
	(StructPatternFieldIdentPat::as_string): Likewise.
	(StructPatternElements::as_string): Likewise.
	(StructPattern::as_string): Likewise.
	(LiteralPattern::as_string): Likewise.
	(ReferencePattern::as_string): Likewise.
	(IdentifierPattern::as_string): Likewise.
	(TupleStructItemsNoRange::as_string): Likewise.
	(TupleStructItemsRange::as_string): Likewise.
	(TupleStructPattern::as_string): Likewise.
	(GroupedExpr::accept_vis): Likewise.
	(LiteralPattern::accept_vis): Likewise.
	(IdentifierPattern::accept_vis): Likewise.
	(WildcardPattern::accept_vis): Likewise.
	(RestPattern::accept_vis): Likewise.
	(RangePatternBoundLiteral::accept_vis): Likewise.
	(RangePatternBoundPath::accept_vis): Likewise.
	(RangePatternBoundQualPath::accept_vis): Likewise.
	(RangePattern::accept_vis): Likewise.
	(ReferencePattern::accept_vis): Likewise.
	(StructPatternFieldTuplePat::accept_vis): Likewise.
	(StructPatternFieldIdentPat::accept_vis): Likewise.
	(StructPatternFieldIdent::accept_vis): Likewise.
	(StructPattern::accept_vis): Likewise.
	(TupleStructItemsNoRange::accept_vis): Likewise.
	(TupleStructItemsRange::accept_vis): Likewise.
	(TupleStructPattern::accept_vis): Likewise.
	(TuplePatternItemsMultiple::accept_vis): Likewise.
	(TuplePatternItemsRanged::accept_vis): Likewise.
	(TuplePattern::accept_vis): Likewise.
	(GroupedPattern::accept_vis): Likewise.
	(SlicePattern::accept_vis): Likewise.
	(AltPattern::accept_vis): Likewise.
	* ast/rust-ast-formatting.cc: New file.
	* ast/rust-ast-formatting.h: New file.
	* ast/rust-pattern.cc: New file.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>