Quote the multipart boundary header parameter value

[chamil321]

Purpose

When setting boundary in the response along with the content type header, the quotes are missing and returns error

HTTP/1.1 200 OK
content-type: multipart/mixed;boundary=------=_Part_0_814051860.1675096572056
content-length: 145
server: ballerina
date: Thu, 16 Feb 2023 11:25:35 +0530  
[2023-02-16 11:25:35,985] TRACE {http.tracelog.upstream} - [id: 0xbbab8c31, correlatedSource: 0x023ca025, host:/127.0.0.1:54241 - remote:localhost/127.0.0.1:9090] INBOUND: DefaultLastHttpContent(data: PooledSlicedByteBuf(ridx: 0, widx: 145, cap: 145/145, unwrapped: PooledUnsafeDirectByteBuf(ridx: 322, widx: 322, cap: 2048)), decoderResult: success), 145B
--------=_Part_0_814051860.1675096572056
content-type: application/json

{"bodyPart":"jsonPart"}
--------=_Part_0_814051860.1675096572056--
  
[2023-02-16 11:25:35,987] TRACE {http.tracelog.upstream} - [id: 0xbbab8c31, correlatedSource: 0x023ca025, host:/127.0.0.1:54241 - remote:localhost/127.0.0.1:9090] READ COMPLETE  
error: {ballerina/mime}ParsingEntityBodyFailed message=Error occurred while decoding body parts from inputstream More characters encountered in input than expected.
        at ballerina.http:externGetResEntity(http_response.bal:475)
           ballerina.http.Response:getEntity(http_response.bal:61)
           ballerina.http.Response:getBodyParts(http_response.bal:294)
           $value$test2__service_1:passthrough(main.bal:118)

[github-actions]

This PR has been open for more than 15 days with no activity. This will be closed in 3 days unless the stale label is removed or commented.

[github-actions]

This PR has been open for more than 15 days with no activity. This will be closed in 3 days unless the stale label is removed or commented.

[github-actions]

Closed PR due to inactivity for more than 18 days.

[anupama-pathirage]

@shafreenAnfar Is this a PR that we can ignore as not needed?