json_view: one SIMD macro set with the library (#5921)

The view's vector code follows JSON_NO_SIMD, like the lexer and the float
writer, and skips the CPU check of SSSE3 when the code is compiled for
SSSE3 anyway (__SSSE3__), like the lexer. JSON_VIEW_NO_SIMD and
JSON_VIEW_USE_SSSE3 and their ABI tags _vns and _vssse3 are removed; they
were never released. JSON_NO_SIMD keeps its tag _ns.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

docs/mkdocs/docs/features/namespace.md

@@ -28,8 +28,6 @@ The complete default namespace name is derived as follows:
     - [`JSON_DISABLE_UNLOCKED_FILE_IO`](../api/macros/json_disable_unlocked_file_io.md) defined non-zero appends
       `_dufio`.
     - [`JSON_NO_SIMD`](../api/macros/json_no_simd.md) defined appends `_ns`.
-    - [`JSON_VIEW_NO_SIMD`](../api/macros/json_view_no_simd.md) defined appends `_vns`.
-    - [`JSON_VIEW_USE_SSSE3`](../api/macros/json_view_use_ssse3.md) defined appends `_vssse3`.
 - The inline namespace ends with the suffix `_v` followed by the 3 components of the version number separated by
   underscores. To omit the version component, see [Disabling the version component](#disabling-the-version-component)
   below.
@@ -115,7 +113,5 @@ follows:
   ([`JSON_STRICT_BINARY_UTF8`](../api/macros/json_strict_binary_utf8.md)), `_ekmo`
   ([`JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS`](../api/macros/json_use_objects_for_enum_keyed_maps.md)), `_dsbs`
   ([`JSON_DISABLE_STREAM_BULK_SCAN`](../api/macros/json_disable_stream_bulk_scan.md)), `_dufio`
-  ([`JSON_DISABLE_UNLOCKED_FILE_IO`](../api/macros/json_disable_unlocked_file_io.md)), `_ns`
-  ([`JSON_NO_SIMD`](../api/macros/json_no_simd.md)), `_vns`
-  ([`JSON_VIEW_NO_SIMD`](../api/macros/json_view_no_simd.md)), and `_vssse3`
-  ([`JSON_VIEW_USE_SSSE3`](../api/macros/json_view_use_ssse3.md)) in version 3.13.0.
+  ([`JSON_DISABLE_UNLOCKED_FILE_IO`](../api/macros/json_disable_unlocked_file_io.md)), and `_ns`
+  ([`JSON_NO_SIMD`](../api/macros/json_no_simd.md)) in version 3.13.0.