Standardise method naming across all HTTP verbs

[DaraOladapo]

Description

The string-returning method family uses inconsistent names depending on the HTTP verb:

Verb	Method name
GET	GetAsStringAsync
POST	PostAndGetResponseAsStringAsync
PUT	PutAndGetResponseAsStringAsync
PATCH	PatchAndGetResponseAsStringAsync
DELETE	DeleteAndGetResponseAsStringAsync

GET uses a shorter, cleaner convention; the other four use a verbose AndGetResponseAsString infix. This creates an inconsistent API surface that surprises callers switching between verbs.

Proposed Fix

Adopt one convention for all verbs. The GET style is more idiomatic:

Old name	New name
PostAndGetResponseAsStringAsync	PostAsStringAsync
PutAndGetResponseAsStringAsync	PutAsStringAsync
PatchAndGetResponseAsStringAsync	PatchAsStringAsync
DeleteAndGetResponseAsStringAsync	DeleteAsStringAsync

Keep the old names as [Obsolete]-decorated overloads for one version cycle to avoid a hard breaking change, then remove them in the next major version.

Acceptance Criteria

• All string-returning methods follow the {Verb}AsStringAsync pattern
• Old verbose names are marked [Obsolete] with a message pointing to the new name
• Tests use the new names
• CHANGELOG / release notes call out the rename