Merge pull request #17570 from HannibalAPE:text_det_recog_demo

[GSoC] High Level API and Samples for Scene Text Detection and Recognition

* APIs and samples for scene text detection and recognition

* update APIs and tutorial for Text Detection and Recognition

* API updates:
(1) put decodeType into struct Voc
(2) optimize the post-processing of DB

* sample update:
(1) add transformation into scene_text_spotting.cpp
(2) modify text_detection.cpp with API update

* update tutorial

* simplify text recognition API
update tutorial

* update impl usage in recognize() and detect()

* dnn: refactoring public API of TextRecognitionModel/TextDetectionModel

* update provided models
update opencv.bib

* dnn: adjust text rectangle angle

* remove points ordering operation in model.cpp

* update gts of DB test in test_model.cpp

* dnn: ensure to keep text rectangle angle

- avoid 90/180 degree turns

* dnn(text): use quadrangle result in TextDetectionModel API

* dnn: update Text Detection API
(1) keep points' order consistent with (bl, tl, tr, br) in unclip
(2) update contourScore with boundingRect

samples/data/alphabet_36.txt

@@ -0,0 +1,36 @@
+0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+a
+b
+c
+d
+e
+f
+g
+h
+i
+j
+k
+l
+m
+n
+o
+p
+q
+r
+s
+t
+u
+v
+w
+x
+y
+z

samples/data/alphabet_94.txt

@@ -0,0 +1,94 @@
+0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+a
+b
+c
+d
+e
+f
+g
+h
+i
+j
+k
+l
+m
+n
+o
+p
+q
+r
+s
+t
+u
+v
+w
+x
+y
+z
+A
+B
+C
+D
+E
+F
+G
+H
+I
+J
+K
+L
+M
+N
+O
+P
+Q
+R
+S
+T
+U
+V
+W
+X
+Y
+Z
+!
+"
+#
+$
+%
+&
+'
+(
+)
+*
++
+,
+-
+.
+/
+:
+;
+<
+=
+>
+?
+@
+[
+\
+]
+^
+_
+`
+{
+|
+}
+~