feat: add authorship arguments to assistant.threads.setStatus and chat.startStream

[zimeg]

This pull request adds authorship arguments (icon_emoji, icon_url, username) to the assistant.threads.setStatus and chat.startStream API methods. Mirrors slackapi/node-slack-sdk#2455.

• Add icon_emoji, icon_url, and username parameters to AssistantThreadsSetStatusRequest
• Add icon_emoji, icon_url, and username parameters to ChatStartStreamRequest
• Add form builder serialization for the new fields in RequestFormBuilder

References:

• https://docs.slack.dev/reference/methods/assistant.threads.setStatus
• https://docs.slack.dev/reference/methods/chat.startStream

Reviewers

Please feel free to experiment with the following code example:

import com.slack.api.Slack;
import com.slack.api.methods.response.chat.ChatStartStreamResponse;

var slack = Slack.getInstance();
var client = slack.methods("xoxb-your-token");

client.assistantThreadsSetStatus(r -> r
    .channelId("C018QLSQ38A")
    .threadTs("1765934795.222209")
    .status("dancing...")
    .username("Charlie Brown")
    .iconEmoji("maple_leaf")
);

Thread.sleep(4000);

ChatStartStreamResponse response = client.chatStartStream(r -> r
    .channel("C018QLSQ38A")
    .threadTs("1765934795.222209")
    .recipientTeamId("T07L2FPUY")
    .recipientUserId("U0187GKV2US")
    .username("Charlie Brown")
    .iconEmoji("maple_leaf")
);

Thread.sleep(2000);

client.chatAppendStream(r -> r
    .channel("C018QLSQ38A")
    .ts(response.getTs())
    .markdownText("Dancing with snoopy dog.")
);

Thread.sleep(2000);

client.chatStopStream(r -> r
    .channel("C018QLSQ38A")
    .ts(response.getTs())
);

Category (place an x in each of the [ ])

• bolt (Bolt for Java)
• bolt-{sub modules} (Bolt for Java - optional modules)
• slack-api-client (Slack API Clients)
• slack-api-model (Slack API Data Models)
• slack-api-*-kotlin-extension (Kotlin Extensions for Slack API Clients)
• slack-app-backend (The primitive layer of Bolt for Java)

Requirements

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you agree to those rules.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.22%. Comparing base (5688130) to head (39d28d5).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...java/com/slack/api/methods/RequestFormBuilder.java	50.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1586      +/-   ##
============================================
+ Coverage     73.20%   73.22%   +0.01%     
- Complexity     4514     4516       +2     
============================================
  Files           477      477              
  Lines         14285    14291       +6     
  Branches       1488     1488              
============================================
+ Hits          10458    10465       +7     
+ Misses         2936     2933       -3     
- Partials        891      893       +2     

Flag	Coverage Δ
jdk-14	73.22% <50.00%> (+0.01%)	⬆️

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