Apply if let shorthand syntax

[mlight3]

if let shorthand syntax was introduced since swift 5.7. (SE-3045)

I replace codes by using following regexs.

regex	replacement
if let (.+)? = \1 {	if let $1 {
if let (.+)? = \1,	if let $1,
if let (.+)? = self.\1 {	if let $1 {
if let (.+)? = self.\1,	if let $1,

[kean]

Nice work, thank you @mlight3.

I noticed there is also at least one var that hasn't been updated, in case you'd want to tackle it as well:

guard var request = request else {

[mlight3]

Hi ,@kean

Thank you for the review.
I also replaced guard statement in this commit