Add `xmake show` plugin to show some builtin configuration values and infos

[waruqi]

• --list=toolchains
• --list=targets
• --list=platforms
• --list=buildmodes
• --list=rules
• --list=packages
• --list=envs
• --toolchain=clang
• --plat=macosx
• --target=xxx
• --package=xxx
• xmake show (basic info)
• support json format output

$ xmake show --list=toolchains
$ xmake show --list=targets
$ xmake show --list=platforms
$ xmake show --list=packages

$ xmake show --toolchain=clang
$ xmake show --plat=macosx
$ xmake show -p macosx
$ xmake show --target=xxx
$ xmake show --package=xxx

[waruqi]

Show basic information xmake show

$ xmake show
The information of xmake:
    version: 2.3.3+202006011009
    host: macosx/x86_64
    programdir: /Users/ruki/.local/share/xmake
    programfile: /Users/ruki/.local/bin/xmake
    globaldir: /Users/ruki/.xmake
    tmpdir: /var/folders/32/w9cz0y_14hs19lkbs6v6_fm80000gn/T/.xmake501/200602
    workingdir: /Users/ruki/projects/personal/tbox
    packagedir: /Users/ruki/.xmake/packages
    packagedir(cache): /Users/ruki/.xmake/cache/packages/2006

The information of project: tbox
    version: 1.6.5
    configdir: /Users/ruki/projects/personal/tbox/.xmake/macosx/x86_64
    projectdir: /Users/ruki/projects/personal/tbox
    projectfile: /Users/ruki/projects/personal/tbox/xmake.lua

[waruqi]

Show the given target infomation xmake show --target=tbox

$ xmake show --target=tbox
The information of target(tbox):
    kind: static
    targetfile: build/macosx/x86_64/release/libtbox.a
    rules: mode.release, mode.debug, mode.profile, mode.coverage
    options: info, float, wchar, exception, force-utf8, deprecated, xml, zip, hash, regex, coroutine, object, charset, database
    packages: mbedtls, polarssl, openssl, pcre2, pcre, zlib, mysql, sqlite3
    links: pthread
    syslinks: pthread, dl, m, c
    cxflags: -Wno-error=deprecated-declarations, -fno-strict-aliasing, -Wno-error=expansion-to-defined, -fno-stack-protector
    defines: __tb_small__, __tb_prefix__="tbox"
    mxflags: -Wno-error=deprecated-declarations, -fno-strict-aliasing, -Wno-error=expansion-to-defined
    headerfiles: src/(tbox/**.h)|**/impl/**.h, src/(tbox/prefix/**/prefix.S), src/(tbox/math/impl/*.h), src/(tbox/utils/impl/*.h), build/macosx/x86_64/release/tbox.config.h
    includedirs: src, build/macosx/x86_64/release
    at: /Users/ruki/projects/personal/tbox/src/tbox/xmake.lua
    sourcebatch(cc): with rule(c.build)
      -> src/tbox/string/static_string.c
         -> build/.objs/tbox/macosx/x86_64/release/src/tbox/string/static_string.c.o
         -> build/.deps/tbox/macosx/x86_64/release/src/tbox/string/static_string.c.o.d
      -> src/tbox/platform/sched.c
         -> build/.objs/tbox/macosx/x86_64/release/src/tbox/platform/sched.c.o
         -> build/.deps/tbox/macosx/x86_64/release/src/tbox/platform/sched.c.o.d
      -> src/tbox/stream/stream.c
         -> build/.objs/tbox/macosx/x86_64/release/src/tbox/stream/stream.c.o
         -> build/.deps/tbox/macosx/x86_64/release/src/tbox/stream/stream.c.o.d
      -> src/tbox/utils/base32.c
         -> build/.objs/tbox/macosx/x86_64/release/src/tbox/utils/base32.c.o
         -> build/.deps/tbox/macosx/x86_64/release/src/tbox/utils/base32.c.o.d

[waruqi]

Show toolchains xmake show -l toolchains

$ xmake show -l toolchains
xcode         Xcode IDE
vs            VisualStudio IDE
yasm          The Yasm Modular Assembler
clang         A C language family frontend for LLVM
go            Go Programming Language Compiler
dlang         D Programming Language Compiler
sdcc          Small Device C Compiler
cuda          CUDA Toolkit
ndk           Android NDK
rust          Rust Programming Language Compiler
llvm          A collection of modular and reusable compiler and toolchain technologies
cross         Common cross compilation toolchain
nasm          NASM Assembler
gcc           GNU Compiler Collection
mingw         Minimalist GNU for Windows
gnu-rm        GNU Arm Embedded Toolchain
envs          Environment variables toolchain
fasm          Flat Assembler

[playgithub]

能不能加个类似xmake show --list=targetpath？
这样的话vscode launch.json就可以引用，而且现在vscodium的插件库独立了，找不到xmake插件了。

[waruqi]

能不能加个类似xmake show --list=targetpath？
这样的话vscode launch.json就可以引用，而且现在vscodium的插件库独立了，找不到xmake插件了。

#836 (comment) 我之前说的方式 试过没有，我发现你也真纠结。。

https://github.com/xmake-io/xmake-vscode/blob/master/assets/targetpath.lua 这里又实现方式，你可以个pr进来。

[playgithub]

xmake show要改哪个文件？

[waruqi]

https://github.com/xmake-io/xmake/tree/master/xmake/plugins/show

另外，命令改成 xmake show --targetpath=xxx

[playgithub]

显示可执行文件的路径，那xxx是什么？

[waruqi]

显示可执行文件的路径，那xxx是什么？

targetname啊，不然一个工程多个target，你要显示那个target路径？

[playgithub]

对
就是--targetpath=xxx不是太直观，我考虑一下