Allow trait bounds to be overridden in macro (#808)

* Parse user defined client_bounds and server_bounds

Signed-off-by: Alexandru Vasile <[email protected]>

* Use custom user defined bounds if provided

Signed-off-by: Alexandru Vasile <[email protected]>

* Add provided where clause to the custom bounds

Signed-off-by: Alexandru Vasile <[email protected]>

* Add proc_macro with bounds example

Signed-off-by: Alexandru Vasile <[email protected]>

* Check against client_bounds wihtout client implementation

Signed-off-by: Alexandru Vasile <[email protected]>

* tests: Add ui test for empty bounds

Signed-off-by: Alexandru Vasile <[email protected]>

* tests: Add ui test to check bounds without implementation

Signed-off-by: Alexandru Vasile <[email protected]>

* Add bounds documentation

Signed-off-by: Alexandru Vasile <[email protected]>

* rpc_macro: Remove `WherePredicate` from parsing

Signed-off-by: Alexandru Vasile <[email protected]>

* ui: Add test that compiles

Signed-off-by: Alexandru Vasile <[email protected]>

* Rename rendered `T` to avoid collision with user provided generic

Signed-off-by: Alexandru Vasile <[email protected]>

* tests: Modify UI correct rpc_bounds test to call server's methods

Signed-off-by: Alexandru Vasile <[email protected]>