support encode for modular

[qiaozha]

add support for encode for datetime, duration, bytes in Modular.

for datetime, Modular layer will always be a Date type, but RLC layer will be different.

1. In the case "rfc7231" or if the default in header, RLC layer will be a utc datetime string.
   serialize: someDate.toUTCString()
   deserialize: Date(someUTCString)
2. In the case of "unixTimestamp", RLC layer will be a number.
   serialize: someDate.getTime()
   deserialize: Date(someUnixTimestamp)
3. In the case of "rfc3339":or default not in header, RLC layer will be a ISO datetime string.
   serialize: someDate.toISOString()
   deserialize: Date(someISOString)

for duration

1. In the case of format "seconds", both Modular and RLC layer will use number.
2. In the case of "ISO8601" or default, both Modular and RLC layer will use string.

for bytes:

1. Modular layer will be Uint8Array and RLC layer will be string no matter what format is using
   serialize: uint8ArrayToString(value, format)
   deserialize: stringToUint8Array(value, format)

fixes #2007

[MaryGao]

Could you point to me where is the fix code?

[MaryGao]

I notice the typespec type here is utcDateTime but we generate to toISOString

https://github.com/Azure/autorest.typescript/blob/1235e0ba4762ac1171f5777b50eafb1b7e43a8d0/packages/typespec-test/test/eventgrid_modular/spec/main.tsp#L64-L65C24

Not sure it is possible to add some UTs to cover typespec type to modular type:

/**
 * A date on a calendar without a time zone, e.g. "April 10th"
 */
scalar plainDate;

/**
 * A time on a clock without a time zone, e.g. "3:00 am"
 */
scalar plainTime;

/**
 * An instant in coordinated universal time (UTC)"
 */
scalar utcDateTime;

/**
 * A date and time in a particular time zone, e.g. "April 10th at 3:00am in PST"
 */
scalar offsetDateTime;

[qiaozha]

I suspect typespec compiler does not provide any format info to these types, but let me check.

[qiaozha]

typescript date.toUTCString() is "Fri, 08 Sep 2023 08:50:03 GMT" and date.toISOString() is "2023-09-08T08:42:49.439Z"
therefore use toISOString for utcDateTime makes more sense. and toUTCString for offsetDateTime makes more sense to me.

[MaryGao]

Yeah, it makes sense to me also. Just checking with Tim here microsoft/typespec#1899 (comment)

[MaryGao]

It seems both of them share the same default value.

https://microsoft.github.io/typespec/next/standard-library/http/encoding#utcdatetime-and-offsetdatetime

[qiaozha]

They are not the same

[MaryGao]

I think the change makes sense for me.

[qiaozha]

It should be here fixing the options.filters

[MaryGao]

LGTM and just left small comments for checking and one ut.