Ensure parsing/toString symmetry in ContentDisposition name

[yashsiwacha]

Closes gh-37064

Overview

Currently, the parsing/toString() process for the name parameter in ContentDisposition is not symmetric when it comes to quoted-pairs (characters like \" and \\).

While ContentDisposition already correctly encodes and decodes quoted-pairs for the filename parameter, the name parameter was written and read as a raw quoted string. As a result, formatting a name containing a quote or backslash produces malformed HTTP headers, and parsing them back yields corrupted names containing unescaped backslashes.

Changes

• Formatting: Updated ContentDisposition.toString() to encode the name parameter using encodeQuotedPairs(this.name).
• Parsing: Updated ContentDisposition.parse() to decode the parsed name value using decodeQuotedPairs(value) if a backslash is present.
• Testing: Added formatAndParseWithNameWithQuotes in ContentDispositionTests to assert formatting and parsing symmetry under nested quotes and backslashes.

[bclozel]

See #37069 (comment)