Redundant effect warnings should have fixits

Description

this is a follow up task to https://github.com/swiftlang/swift/issues/85818 – in working on that issue, it appeared that the other 'redundant effect' warnings also generally lack fixits that will remove the unneeded effect markers. specifically, we should support fixits for redundant try and unsafe on expressions that do not produce those effects. the 'single value expression' diagnostic variants should also be handled in these cases.

Reproduction

no fixits are produced for these:

@discardableResult
func g() -> Int? { nil }

_ = try g()
_ = try switch g() { default: 0 }
_ = unsafe switch g() { default: 0 }

12 | func g() -> Int? { nil }
13 | 
14 | _ = try g()
   |     `- warning: no calls to throwing functions occur within 'try' expression [no_throw_in_try]
15 | _ = try switch g() { default: 0 }
16 | _ = unsafe switch g() { default: 0 }

13 | 
14 | _ = try g()
15 | _ = try switch g() { default: 0 }
   |     `- warning: 'try' has no effect on 'switch' expression [effect_marker_on_single_value_stmt]
16 | _ = unsafe switch g() { default: 0 }
17 | 

14 | _ = try g()
15 | _ = try switch g() { default: 0 }
16 | _ = unsafe switch g() { default: 0 }
   |     `- warning: 'unsafe' has no effect on 'switch' expression [effect_marker_on_single_value_stmt]
17 | 

Expected behavior

the redundant effect markers should have fixits offering to remove them

Environment

Swift version 6.3-dev (LLVM 35f48306184cd25, Swift a69dbb3366e64d8) Target: x86_64-unknown-linux-gnu

Additional information

No response