BUG: Handle prefix whitespace when guessing WKT dialiect

Author: Alan Snow

src/iso19111/io.cpp

@@ -8015,7 +8015,12 @@ WKTParser::attachDatabaseContext(const DatabaseContextPtr &dbContext) {
 /** \brief Guess the "dialect" of the WKT string.
  */
 WKTParser::WKTGuessedDialect
-WKTParser::guessDialect(const std::string &wkt) noexcept {
+WKTParser::guessDialect(const std::string &inputWkt) noexcept {
+    std::string wkt = inputWkt;
+    std::size_t idxFirstCharNotSpace = wkt.find_first_not_of(" \t\r\n");
+    if (idxFirstCharNotSpace > 0 && idxFirstCharNotSpace != std::string::npos) {
+        wkt = wkt.substr(idxFirstCharNotSpace);
+    }
     if (ci_starts_with(wkt, WKTConstants::VERTCS)) {
         return WKTGuessedDialect::WKT1_ESRI;
     }

test/unit/test_c_api.cpp

@@ -2227,7 +2227,7 @@ TEST_F(CApi, proj_context_guess_wkt_dialect) {
 
     EXPECT_EQ(proj_context_guess_wkt_dialect(
                   nullptr,
-                  "GEOGCRS[\"WGS 84\",\n"
+                  " \n\t\rGEOGCRS[\"WGS 84\",\n"
                   "    DATUM[\"World Geodetic System 1984\",\n"
                   "        ELLIPSOID[\"WGS 84\",6378137,298.257223563]],\n"
                   "    CS[ellipsoidal,2],\n"