Revert "Introduce generic fluent client generator to non-sdk codegen"

[rcoh]

Reverts awslabs/smithy-rs#463

Seeing weird stack overflow / infinite recursion issues:

    frame #8735: 0x000000010000bf01 ec2-helloworld`_$LT$T$u20$as$u20$smithy_client..erase..boxclone..CloneService$LT$Request$GT$$GT$::clone_box::h010c647f0a4ff9b5(self=0x0000000101e34380) at boxclone.rs:76:18
    frame #8736: 0x000000010000afb1 ec2-helloworld`_$LT$smithy_client..erase..boxclone..BoxCloneService$LT$T$C$U$C$E$GT$$u20$as$u20$core..clone..Clone$GT$::clone::hbe330dc7abb063d9(self=0x0000000101e34380) at boxclone.rs:115:20
    frame #8737: 0x000000010000bf01 ec2-helloworld`_$LT$T$u20$as$u20$smithy_client..erase..boxclone..CloneService$LT$Request$GT$$GT$::clone_box::h010c647f0a4ff9b5(self=0x0000000101e34380) at boxclone.rs:76:18
    frame #8738: 0x000000010000afb1 ec2-helloworld`_$LT$smithy_client..erase..boxclone..BoxCloneService$LT$T$C$U$C$E$GT$$u20$as$u20$core..clone..Clone$GT$::clone::hbe330dc7abb063d9(self=0x0000000101e34380) at boxclone.rs:115:20
    frame #8739: 0x000000010000bf01 ec2-helloworld`_$LT$T$u20$as$u20$smithy_client..erase..boxclone..CloneService$LT$Request$GT$$GT$::clone_box::h010c647f0a4ff9b5(self=0x0000000101e34380) at boxclone.rs:76:18
    frame #8740: 0x000000010000afb1 ec2-helloworld`_$LT$smithy_client..erase..boxclone..BoxCloneService$LT$T$C$U$C$E$GT$$u20$as$u20$core..clone..Clone$GT$::clone::hbe330dc7abb063d9(self=0x0000000101e34380) at boxclone.rs:C115:20

[jonhoo]

Ah, yes, this line:
https://github.com/jonhoo/smithy-rs/blob/3f59c58ae843e08a9b9e8c967e8ec3897b235719/rust-runtime/smithy-client/src/erase/boxclone.rs#L115

Should be self.inner.clone().