[FEATURE] Add option to configure the picker window size

[rafaelnp]

Is your feature request related to a problem? Please describe.
there is at the moment, AFAIK, no option to resize the picker window

Describe the solution you'd like
Add the configuration option to define the picker window size (e.g. percentage of neovim window)

Describe alternatives you've considered
none

Additional context
none

[cameronr]

It's not well documented, but you can use the theme_conf config option to change the size of the picker. The easiest way to see the options is to look at the code:

https://github.com/nvim-telescope/telescope.nvim/blob/5972437de807c3bc101565175da66a1aa4f8707a/lua/telescope/themes.lua#L41

Adding this to your auto-session config sets the picker to 80% of the width and 50% of the height:

      ...
      session_lens = {
        theme_conf = {
          layout_config = {
            width = 0.8,
            height = 0.5,
          },
        },
      },

It also looks like there's a bug when setting it to 100% where you have to specify that slightly differently:
nvim-telescope/telescope.nvim#2508 (comment)

Does that help you do what you want? Assuming yes, what size do you want to make it (I'm just curious)?

If this solves it for you, I'll add some more documentation to the readme.

[rafaelnp]

@cameronr Thanks for your suggestion and sorry for the late reply. Yes, it does work for me. 👍

[cameronr]

I'm doing a larger config overhaul so will include the docs in that.