refactor!: Split RepositoryComment request bodies and pass by value

[JamBalaya56562]

Continues the request-body-by-value work in #3644 — the commit-comments counterpart of #4444 (IssueComment, issues) and #4493 (PullRequestComment, pulls), completing the comment-endpoint family.

Commit 1 (refactor!:) — RepositoriesService.CreateComment and UpdateComment reused the 12-field RepositoryComment response type as their request bodies. Per the create / update docs the two request schemas differ, so this splits them into dedicated types (same shape as #4493):

	body	path	position	line
create	required	optional	optional	optional (deprecated — "use position instead")
update	required	—	—	—

type CreateCommitCommentRequest struct {
	Body     string  `json:"body"`
	Path     *string `json:"path,omitempty"`
	Position *int    `json:"position,omitempty"`
	// Deprecated: Use Position instead.
	Line *int `json:"line,omitempty"`
}

type UpdateCommitCommentRequest struct {
	Body string `json:"body"`
}

Both methods now take these by value (Body required → non-pointer, no omitempty), and RepositoryComment is removed from the paramcheck allowlist in .golangci.yml. No method renames are needed — Create/Update already match the docs operation names. Alongside:

• the now-stale // User-mutable fields / // User-initialized fields markers on RepositoryComment are dropped and Body's tag normalized to json:"body,omitempty", making it a plain response type like IssueComment / PullRequestComment;
• the {comment_id} parameter is named commentID consistently across GetComment / UpdateComment / DeleteComment (matching the issues/pulls comment files);
• the request types also gain the deprecated line create parameter, which the old shared type could not send at all.

Commit 2 (feat:, non-breaking) — cross-checking the full commit-comment response schema against the struct turned up two missing fields, added here with regenerated accessors: AuthorAssociation and Line.

BREAKING CHANGE: RepositoriesService.CreateComment now takes CreateCommitCommentRequest and RepositoriesService.UpdateComment takes UpdateCommitCommentRequest, both passed by value instead of *RepositoryComment.

Verified with go build ./..., gofmt, go vet -tags integration ./test/integration/, the full ./github/ test suite (all repos_comments.go methods at 100% coverage), generator idempotency, and custom-gcl (0 issues with the allowlist entry removed).

Updates #3644.

cc @jvm986

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.52%. Comparing base (95224ef) to head (b85f7af).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4496   +/-   ##
=======================================
  Coverage   98.52%   98.52%           
=======================================
  Files         195      195           
  Lines       17745    17745           
=======================================
  Hits        17484    17484           
  Misses        261      261           

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[gmlewis]

Thank you, @JamBalaya56562!
LGTM.
Awaiting second LGTM+Approval from any other contributor to this repo before merging.

cc: @stevehipwell - @alexandear - @Not-Dhananjay-Mishra