[typescript-angular] Missing 'override's in encoder.ts

[repolevedavaj]

Since typescript 4.3.0, there is support for adding the keyword override to methods overriding the super method. The usage of this keyword can be enforced by activating noImplicitOverride in the tsconfig.json. If you generate a new Angular project, this flag is set to true`, therefore the compilation fails with the following error message:

encoder.ts:13:5 - error TS4114: This member must have an 'override' modifier because it overrides a member in the base class 'HttpUrlEncodingCodec'.

It would be nice if you could add this keyword to the template. This will break clients using Typescript < 4.3.0.