cmListFileLexer: Allow command names with one letter (#14181)

Teach the lexer to treat a single letter as an identifier instead of an
unquoted argument.  Outside of a command invocation, the parser treats
an identifier as a command name and an unquoted argument as an error.
Inside of a command invocation, the parser treats an identifier as an
unquoted argument.  Therefore this change to the lexer will make what
was previously an error case work with no other behavioral change.
cmListFileLexer: Allow a leading UTF-8 Byte-Order-Mark (#11137)

Teach the lexer to read a UTF-8, UTF-16 BE/LE, or UTF-32 BE/LE
Byte-Order-Mark from the start of a file if any is present.  Report an
error on files using UTF-16 or UTF-32 and accept a UTF-8 or missing BOM.
cmListFileLexer: Convert CRLF -> LF newlines explicitly

Read input files in binary mode instead of text mode and convert CRLF
newlines to LF newlines explicitly in our own buffer.  This is necessary
to read CMake source files with CRLF newlines on platforms whose C
runtime libraries do not transform newlines in text mode.  For example,
a Cygwin or Linux binary may not transform CRLF -> LF in files read from
a Windows filesystem.  Perform the conversion ourselves to ensure that
multi-line string literals in CMake source files have LF newlines
everywhere.
Add Lua-style long brackets and long comments to CMake language

Teach the CMake language parser to recognize Lua-style "long bracket"
arguments.  These start with two '[' separated by zero or more '='
characters e.g. "[[" or "[=[" or "[==[".  They end with two ']'
separated by the same number of '=' as the opening bracket.  There is no
nesting of brackets of the same level (number of '=').  No escapes,
variable expansion, or other processing is performed on the content
between such brackets so they always represent exactly one argument.

Also teach CMake to parse and ignore "long comment" syntax.  A long
comment starts with "#" immediately followed by an opening long bracket.
It ends at the matching close long bracket.

Teach the RunCMake.Syntax test to cover long bracket and long comment
cases.
Merge topic 'cmake-syntax-updates' into next

daa0f6f Add Lua-style long brackets and long comments to CMake language
a8c6523 cmListFileLexer: Convert CRLF -> LF newlines explicitly
dbd9333 cmListFileLexer: Allow a leading UTF-8 Byte-Order-Mark (#11137)
5645783 cmListFileLexer: Allow command names with one letter (#14181)