Vapor: 4.15.2 Release

This patch was authored and released by @tanner0101.

Adds support for percent-encoded brackets in query strings (fixes #2383, #2384, #2432).

Percent-encoded square brackets are now parsed as array or dictionary delimiters in query strings. For example, both of the following query strings are now equivalent:

page[offset]=0&page[limit]=50
page%5Boffset%5D=0&page%5Blimit%5D=50

Both query strings can now be decoded by the following struct:

struct Info {
    struct Page {
        var offset: Int
        var limit: Int
    }
    let page: Page
}

Previously, the percent-encoded brackets were ignored during array and dictionary parsing.

This change brings Vapor 4's behavior in line with Vapor 3 and other frameworks.