add initial module files

add first function for creating an access token

public/Get-MatrixLoginToken.ps1

@@ -0,0 +1,45 @@
+<#
+    .Synopsis
+    Login and retrieve an Access token.
+
+    .Description
+    Login and retrieve an Access token from _matrix/client/v3/login. See https://spec.matrix.org/v1.2/client-server-api/#post_matrixclientv3login.
+
+    .Parameter ServerUrl
+    URL for the Matrix server to log into, for example "https://matrix.example.com".
+
+    .Parameter Credentials
+    PSCredentials Object that contains the Matrix Username and Password for the user you wish to log in with.
+
+    .Example
+    # Create a PSCredentials Object
+    $creds = Get-Credential
+    $token = Get-LoginToken -ServerUrl "https://matrix.example.com" -Credentials $creds
+#>
+function Get-MatrixLoginToken {
+    param(
+        [Parameter(Mandatory)]
+        [string]$ServerUrl,
+
+        [Parameter(Mandatory)]
+        [PSCredential]$Credentials
+    )
+
+    $apiPath = "_matrix/client/v3/login"
+    $apiMethod = "Post"
+
+    $reqBody = @{
+        identifier = @{
+            type = "m.id.user"
+            user = $Credentials.UserName
+        }
+        type = "m.login.password"
+        password = $Credentials.Password | ConvertFrom-SecureString -AsPlainText
+    } | ConvertTo-Json
+
+    $res = Invoke-RestMethod -Uri "$ServerUrl/$apiPath" -Method $apiMethod -Body $reqBody
+
+    $token = $res.access_token | ConvertTo-SecureString
+
+    return $res.access_token
+}