Fixups for rust-server hyper1 support

[dsteeley]

Fixup minor bugs found in detailed testing of latest rust-server generator.

1. Invalid variable names when using reserved terms.
2. Invalid traits when field has no type specified.
3. Mishandling of data types for application/gzip endpoints.
4. Empty default field when a default isn't specified for enum types.

Fixed 1 by not using the r# prefixing when an endpoint matches a reserved name, this broke compilation as the sanitized name was used in the middle of variable names which was invalid syntax.
Fixed 2 by not appending the PartialOrd trait when the type was unspecified.
Fixed 3 by handling isBinary in various sections of the templates.
Fixed 4 by automatically generating default value from enum entry.

Tested on a variety of API documents for compilation, clippy and tests passing.

Fixed 4 for rust-server-deprecated so tests for that generator pass.

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[wing328]

thanks for the PR

let's give it a try