Support numberic textDocumentSync capability

## Information

**VIM version**

VIM - Vi IMproved 8.2 (2019 Dec 12, compiled Dec 17 2021 18:32:08)
macOS version - x86_64
Included patches: 1-2671, 3402, 3409, 3428, 3489

Operating System: MacOS Monterey 12.2.1

## What went wrong

According to the [spec](https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_synchronization), language servers are allowed to return a number for the `textDocumentSync` capability, rather than a dictionary of specific values (the `purescript-language-server` does this for instance), but [this](https://github.com/dense-analysis/ale/pull/3930/files) change prevents these servers running on save events.

After much digging (hard to track down since the server and ALE are all working correctly. including omnicomplete, etc.) I have rather crudely fixed this locally with this patch

```
M autoload/ale/lsp.vim
@@ -292,6 +292,9 @@ function! s:UpdateCapabilities(conn, capabilities) abort
let a:conn.capabilities.includeText = 1
endif
endif
+ elseif type(get(a:capabilities, 'textDocumentSync')) is v:t_number
+ \&& get(a:capabilities, 'textDocumentSync') > 0 " 1 = Full 2 = Incremental
+ let a:conn.capabilities.did_save = 1
endif
endfunction
```

I'm afaird I don't know enough about vimscript to say if this is the right way or to update tests...

## Reproducing the bug

1. Use a language server which privodes a numberic `textDocumentSync` value (eg. `purescript-language-server`)
2. Save a file
3. Observe no diagnostics, no logs in ALE or the language server

### :ALEInfo

```

Current Filetype: purescript
Available Linters: ['purescript-language-server']
Enabled Linters: ['purescript-language-server']
Ignored Linters: []
Suggested Fixers:
'purs-tidy' - Format PureScript files with purs-tidy.
'purty' - Format PureScript files with purty.
'remove_trailing_lines' - Remove all blank lines at the end of a file.
'trim_whitespace' - Remove all trailing whitespace characters at the end of every line.
Linter Variables:

let g:ale_purescript_ls_config = {'purescript': {'addSpagoSources': v:true, 'addNpmPath': v:true, 'buildCommand': 'spago --quiet build --purs-args --json-errors'}}
let g:ale_purescript_ls_executable = 'purescript-language-server'
let g:ale_purescript_ls_use_global = 0
Global Variables:

let g:ale_cache_executable_check_failures = v:null
let g:ale_change_sign_column_color = v:null
let g:ale_command_wrapper = ''
let g:ale_completion_delay = v:null
let g:ale_completion_enabled = 0
let g:ale_completion_max_suggestions = 1000
let g:ale_disable_lsp = 0
let g:ale_echo_cursor = 1
let g:ale_echo_msg_error_str = 'Error'
let g:ale_echo_msg_format = '%code: %%s'
let g:ale_echo_msg_info_str = 'Info'
let g:ale_echo_msg_warning_str = 'Warning'
let g:ale_enabled = 1
let g:ale_fix_on_save = 0
let g:ale_fixers = {'purescript': ['purs-tidy']}
let g:ale_history_enabled = 1
let g:ale_history_log_output = 1
let g:ale_keep_list_window_open = v:null
let g:ale_lint_delay = 200
let g:ale_lint_on_enter = 1
let g:ale_lint_on_filetype_changed = 1
let g:ale_lint_on_insert_leave = 0
let g:ale_lint_on_save = 1
let g:ale_lint_on_text_changed = 'never'
let g:ale_linter_aliases = {}
let g:ale_linters = {}
let g:ale_linters_explicit = 0
let g:ale_linters_ignore = {}
let g:ale_list_vertical = v:null
let g:ale_list_window_size = v:null
let g:ale_loclist_msg_format = v:null
let g:ale_max_buffer_history_size = 20
let g:ale_max_signs = v:null
let g:ale_maximum_file_size = v:null
let g:ale_open_list = v:null
let g:ale_pattern_options = v:null
let g:ale_pattern_options_enabled = v:null
let g:ale_root = {}
let g:ale_set_balloons = 0
let g:ale_set_highlights = 1
let g:ale_set_loclist = 1
let g:ale_set_quickfix = 0
let g:ale_set_signs = 1
let g:ale_sign_column_always = v:null
let g:ale_sign_error = v:null
let g:ale_sign_info = v:null
let g:ale_sign_offset = v:null
let g:ale_sign_style_error = '~>'
let g:ale_sign_style_warning = '~~'
let g:ale_sign_warning = v:null
let g:ale_sign_highlight_linenrs = v:null
let g:ale_statusline_format = v:null
let g:ale_type_map = {}
let g:ale_use_global_executables = v:null
let g:ale_virtualtext_cursor = 0
let g:ale_warn_about_trailing_blank_lines = 1
let g:ale_warn_about_trailing_whitespace = 1
Command History:

(executable check - success) /node_modules/.bin/purescript-language-server
(started) ['/bin/bash', '-c', '''/node_modules/.bin/purescript-language-server'' --stdio']
```